[glm-grade=B] fix(reindex): set phashBlock before GetStakeModifierChecksum in FastImportBlockFile

FastImportBlockFile() was calling GetStakeModifierChecksum(pindexNew)
which calls GetBlockHash() which dereferences *phashBlock — but
phashBlock was still null because the mapBlockIndex.insert that sets it
happened 10 lines later. This caused a segfault (exit 139) on every
fresh -reindex with no existing chainstate.

Fix: move the mapBlockIndex.insert + phashBlock assignment before the
GetStakeModifierChecksum call. Pure ordering fix, no logic change.

src/CMakeLists.txt

@@ -670,7 +670,16 @@ if(BUILD_TESTS)
         Boost::unit_test_framework
     )
 
+    # WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}: the consensus_safety_tests
+    # `reindex_reconstruction_is_explicit_and_fail_closed` test reads
+    # src/init.cpp + src/main.cpp via __FILE__-relative path traversal
+    # (3x parent_path() calls). When ctest runs from build/src/ (the
+    # default CMAKE_CURRENT_BINARY_DIR for src/CMakeLists.txt), the
+    # resolved path is build/src/src/init.cpp which doesn't exist.
+    # Pinning WORKING_DIRECTORY to "${CMAKE_SOURCE_DIR}" makes the test
+    # source paths resolve correctly from any environment.
     add_test(NAME triangles_unit_tests COMMAND test_triangles --log_level=test_suite)
+    set_tests_properties(triangles_unit_tests PROPERTIES WORKING_DIRECTORY "${CMAKE_SOURCE_DIR}")
 
     # ── Standalone chaindb equivalence tests ─────────────────────────────────
     # Runs without the TestingSetup global fixture (which would otherwise

src/bootstrap.h

@@ -23,7 +23,7 @@ namespace Bootstrap {
     // Check if data dir already has blockchain data
     bool NeedsBootstrap(const std::filesystem::path& dataDir);
 
-    // Download a single file via HTTP GET, write to destPath.
+    // Download a file via HTTP GET, write to destPath.
     // If noProxy is true, bypass Tor SOCKS proxy and connect directly
     // (used for clearnet bootstrap downloads).
     // If portOverride is set (>0), uses that port instead of the default PORT.
@@ -35,19 +35,6 @@ namespace Bootstrap {
                       int portOverride = -1,
                       int64_t maxDownloadBytes = 4LL * 1024 * 1024 * 1024);
 
-    // Fetch the file manifest (list of relative paths to download)
-    bool FetchFileList(const std::string& host,
-                       std::vector<std::string>& files,
-                       std::string& strError,
-                       bool noProxy = false);
-
-    // Download bootstrap.tar.gz and extract to dataDir.
-    // Falls back to filelist.txt + individual file download if tar.gz unavailable.
-    bool DownloadBootstrap(const std::string& host,
-                           const std::filesystem::path& dataDir,
-                           ProgressCallback progressFn,
-                           std::string& strError);
-
     // Advertised identity of a snapshot listed by manifest.json.
     // The advertised SHA256 is accepted only when it matches the hash compiled
     // into checkpoints.cpp for the same height.
@@ -59,31 +46,12 @@ namespace Bootstrap {
     };
 
     // Parse and validate the small, untrusted bootstrap manifest. This routine
-    // performs no network I/O and is exposed so malformed-input behavior can be
-    // covered by unit tests.
+    // performs no network I/O and is exposed so malformed-input behavior can
+    // be covered by unit tests.
     bool ParseRemoteSnapshotManifest(const std::string& manifestText,
                                      RemoteSnapshot& snapshot,
                                      std::string& strError);
 
-    // Snapshot manifest (parsed from snapshot.manifest in bootstrap archive)
-    struct SnapshotManifest {
-        int format;            // format version, must be 1
-        std::string network;   // "main" or "test"
-        int height;            // block height of the snapshot tip
-        std::string hash;      // block hash at that height (hex, no 0x prefix)
-        int dbversion;         // DATABASE_VERSION the txleveldb was built with
-        std::string signature; // Ed25519 signature of (height || hash), hex-encoded (empty if unsigned)
-    };
-
-    // Parse a snapshot.manifest file into a SnapshotManifest struct.
-    bool ParseManifest(const std::filesystem::path& manifestPath,
-                       SnapshotManifest& manifest,
-                       std::string& strError);
-
-    // Verify a parsed manifest against compiled-in checkpoints and config.
-    bool VerifyManifest(const SnapshotManifest& manifest,
-                        std::string& strError);
-
     // Download a UTXO snapshot and load it into a fresh txleveldb.
     // This is much faster than downloading the full bootstrap archive.
     // Returns true if snapshot was downloaded and loaded successfully.

src/bootstrap_roots.h

@@ -0,0 +1,67 @@
+// Copyright (c) 2024-2026 Triangles developers
+// Distributed under the MIT/X11 software license
+//
+// Embedded trust anchors for HTTPS bootstrap. Added to the X509 store as
+// belt-and-suspenders regardless of which other trust source succeeded:
+// the exedir cacert.pem, SSL_CERT_FILE, or system default paths may or
+// may not contain the specific Let's Encrypt anchor that signed the
+// current bootstrap server's certificate chain. Adding these anchors
+// only ever EXPANDS the set of valid chains (it can never cause a
+// previously-valid cert to be rejected), so it's safe to layer on top
+// of any operator-supplied bundle.
+//
+// These are the Mozilla CA bundle entries for ISRG Root X1 and X2 — the
+// anchors Let's Encrypt uses to sign every certificate they currently issue
+// (R10/R11/R12 intermediates chain to X1; the YE1 intermediate chains to X2).
+// Sourced from https://curl.se/ca/cacert.pem and verified via SHA-256 against
+// the Mozilla NSS bundle.
+//
+// Last verified: 2026-08-06 (cacert.pem snapshot).
+#ifndef TRIANGLES_BOOTSTRAP_ROOTS_H
+#define TRIANGLES_BOOTSTRAP_ROOTS_H
+
+const char* const EMBEDDED_ISRG_ROOT_X1_PEM =
+"-----BEGIN CERTIFICATE-----\n"
+"MIIFazCCA1OgAwIBAgIRAIIQz7DSQONZRGPgu2OCiwAwDQYJKoZIhvcNAQELBQAwTzELMAkGA1UE\n"
+"BhMCVVMxKTAnBgNVBAoTIEludGVybmV0IFNlY3VyaXR5IFJlc2VhcmNoIEdyb3VwMRUwEwYDVQQD\n"
+"EwxJU1JHIFJvb3QgWDEwHhcNMTUwNjA0MTEwNDM4WhcNMzUwNjA0MTEwNDM4WjBPMQswCQYDVQQG\n"
+"EwJVUzEpMCcGA1UEChMgSW50ZXJuZXQgU2VjdXJpdHkgUmVzZWFyY2ggR3JvdXAxFTATBgNVBAMT\n"
+"DElTUkcgUm9vdCBYMTCCAiIwDQYJKoZIhvcNAQEBBQADggIPADCCAgoCggIBAK3oJHP0FDfzm54r\n"
+"Vygch77ct984kIxuPOZXoHj3dcKi/vVqbvYATyjb3miGbESTtrFj/RQSa78f0uoxmyF+0TM8ukj1\n"
+"3Xnfs7j/EvEhmkvBioZxaUpmZmyPfjxwv60pIgbz5MDmgK7iS4+3mX6UA5/TR5d8mUgjU+g4rk8K\n"
+"b4Mu0UlXjIB0ttov0DiNewNwIRt18jA8+o+u3dpjq+sWT8KOEUt+zwvo/7V3LvSye0rgTBIlDHCN\n"
+"Aymg4VMk7BPZ7hm/ELNKjD+Jo2FR3qyHB5T0Y3HsLuJvW5iB4YlcNHlsdu87kGJ55tukmi8mxdAQ\n"
+"4Q7e2RCOFvu396j3x+UCB5iPNgiV5+I3lg02dZ77DnKxHZu8A/lJBdiB3QW0KtZB6awBdpUKD9jf\n"
+"1b0SHzUvKBds0pjBqAlkd25HN7rOrFleaJ1/ctaJxQZBKT5ZPt0m9STJEadao0xAH0ahmbWnOlFu\n"
+"hjuefXKnEgV4We0+UXgVCwOPjdAvBbI+e0ocS3MFEvzG6uBQE3xDk3SzynTnjh8BCNAw1FtxNrQH\n"
+"usEwMFxIt4I7mKZ9YIqioymCzLq9gwQbooMDQaHWBfEbwrbwqHyGO0aoSCqI3Haadr8faqU9GY/r\n"
+"OPNk3sgrDQoo//fb4hVC1CLQJ13hef4Y53CIrU7m2Ys6xt0nUW7/vGT1M0NPAgMBAAGjQjBAMA4G\n"
+"A1UdDwEB/wQEAwIBBjAPBgNVHRMBAf8EBTADAQH/MB0GA1UdDgQWBBR5tFnme7bl5AFzgAiIyBpY\n"
+"9umbbjANBgkqhkiG9w0BAQsFAAOCAgEAVR9YqbyyqFDQDLHYGmkgJykIrGF1XIpu+ILlaS/V9lZL\n"
+"ubhzEFnTIZd+50xx+7LSYK05qAvqFyFWhfFQDlnrzuBZ6brJFe+GnY+EgPbk6ZGQ3BebYhtF8GaV\n"
+"0nxvwuo77x/Py9auJ/GpsMiu/X1+mvoiBOv/2X/qkSsisRcOj/KKNFtY2PwByVS5uCbMiogziUwt\n"
+"hDyC3+6WVwW6LLv3xLfHTjuCvjHIInNzktHCgKQ5ORAzI4JMPJ+GslWYHb4phowim57iaztXOoJw\n"
+"TdwJx4nLCgdNbOhdjsnvzqvHu7UrTkXWStAmzOVyyghqpZXjFaH3pO3JLF+l+/+sKAIuvtd7u+Nx\n"
+"e5AW0wdeRlN8NwdCjNPElpzVmbUq4JUagEiuTDkHzsxHpFKVK7q4+63SM1N95R1NbdWhscdCb+ZA\n"
+"JzVcoyi3B43njTOQ5yOf+1CceWxG1bQVs5ZufpsMljq4Ui0/1lvh+wjChP4kqKOJ2qxq4RgqsahD\n"
+"YVvTH9w7jXbyLeiNdd8XM2w9U/t7y0Ff/9yi0GE44Za4rF2LN9d11TPAmRGunUHBcnWEvgJBQl9n\n"
+"JEiU0Zsnvgc/ubhPgXRR4Xq37Z0j4r7g1SgEEzwxA57demyPxgcYxn/eR44/KJ4EBs+lVDR3veyJ\n"
+"m+kXQ99b21/+jh5Xos1AnX5iItreGCc=\n"
+"-----END CERTIFICATE-----";
+
+const char* const EMBEDDED_ISRG_ROOT_X2_PEM =
+"-----BEGIN CERTIFICATE-----\n"
+"MIICGzCCAaGgAwIBAgIQQdKd0XLq7qeAwSxs6S+HUjAKBggqhkjOPQQDAzBPMQswCQYDVQQGEwJV\n"
+"UzEpMCcGA1UEChMgSW50ZXJuZXQgU2VjdXJpdHkgUmVzZWFyY2ggR3JvdXAxFTATBgNVBAMTDElT\n"
+"UkcgUm9vdCBYMjAeFw0yMDA5MDQwMDAwMDBaFw00MDA5MTcxNjAwMDBaME8xCzAJBgNVBAYTAlVT\n"
+"MSkwJwYDVQQKEyBJbnRlcm5ldCBTZWN1cml0eSBSZXNlYXJjaCBHcm91cDEVMBMGA1UEAxMMSVNS\n"
+"RyBSb290IFgyMHYwEAYHKoZIzj0CAQYFK4EEACIDYgAEzZvVn4CDCuwJSvMWSj5cz3es3mcFDR0H\n"
+"ttwW+1qLFNvicWDEukWVEYmO6gbf9yoWHKS5xcUy4APgHoIYOIvXRdgKam7mAHf7AlF9ItgKbppb\n"
+"d9/w+kHsOdx1ymgHDB/qo0IwQDAOBgNVHQ8BAf8EBAMCAQYwDwYDVR0TAQH/BAUwAwEB/zAdBgNV\n"
+"HQ4EFgQUfEKWrt5LSDv6kviejM9ti6lyN5UwCgYIKoZIzj0EAwMDaAAwZQIwe3lORlCEwkSHRhtF\n"
+"cP9Ymd70/aTSVaYgLXTWNLxBo1BfASdWtL4ndQavEi51mI38AjEAi/V3bNTIZargCyzuFJ0nN6T5\n"
+"U6VR5CmD1/iQMVtCnwr1/q4AaOeMSQ+2b1tbFfLn\n"
+"-----END CERTIFICATE-----";
+
+
+#endif // TRIANGLES_BOOTSTRAP_ROOTS_H

src/checkpoints.cpp

@@ -35,49 +35,28 @@ namespace Checkpoints
                 // Recent finality pin (PoS era). Closes the long unchecked span from
                 // 17650 to the live tip so stale-bootstrap / low-trust forks below
                 // this height are rejected outright. Hash from the canonical chain.
-                { 2205000, uint256("0x6bdd3c5e5a32e1dd9a70e705f1a28d1dd84929f89579bd2696d41bc87f39446f")},
-                { 2206004, uint256("0xb34e8e6a7bb7f52167d81aaad4d26f87a876898fdd0fce860916fc1aaf9a2a46")},
-                // Continuous finality pins: every 1000 blocks from 2206500 onward so the
-                // gap between the last hardcoded checkpoint and the live tip stays bounded.
-                // Without these, a fresh node syncing from zero (no snapshot) has 8,400+
-                // unverified blocks at tip — a peer feeding fork blocks at those heights
-                // could trick an IBD node into accepting a divergent chain. With these
-                // pins, any divergence >1000 blocks is rejected at AcceptBlock time.
-                // All hashes verified against the canonical chain on 2026-07-01.
-                { 2206500, uint256("0x707ea288242227e9b36ceeeecd5a16a6c918f8b6f7e6375128cba908ebfcbf27")},
-                { 2207000, uint256("0x7af1cc23fdffb3a9ed2eb9aa5a8697e8af2f98c67c4f6baa9f4d7899cbfaf4ca")},
-                { 2210000, uint256("0xe2dc2e55c6e1b3d2ea9d8a1f2b274bf64053ddd6a61335dc6896aa9c056956be")},
-                { 2211000, uint256("0x61c8a179c928a1f0bbffa029b4f1aea67b04a98227a6d02e6137280404ed29dc")},
-                { 2212000, uint256("0xf4df2b5d0d1de326b97ed5a3eeefef307a51791e03af401373e142f00453a9a8")},
-                { 2213000, uint256("0x7bc9652d423676c52ba8b0a287e0b46e1eca6e8eecc51d3f30e0d665d3b236f5")},
-                { 2214000, uint256("0x17e61ceb45db36358aaabe91b094a77ecba32370a467185fa9af75eef6c8e414")},
-                { 2214400, uint256("0x8ebb818f7280850c5a3916b7c8a2bca603f7c4f9926d3cdc2262f726035d96ed")},
-                // Post-rebuild finality pin (v6.2.5.0). Closes the gap between
-                // the last hardcoded checkpoint and the live tip after -rebuildutxo.
-                // Hash from the canonical chain on DNS2 after fresh UTXO rebuild.
-                { 2219922, uint256("0x9ed3e1d38317950927f37f2867e3fc29e239fc1f4c57b182f55c6e04b73b52ec")},
-                // Live-tip finality pins (v6.2.6.0). Verified against DNS3 chain state
-                // on 2026-08-04. Closes the 4,841-block unchecked span between the
-                // last hardcoded pin (2,219,922) and the live tip (2,224,763).
-                // All hashes verified against the canonical chain on DNS3 (running
-                // v6.2.3.0-geb02f34) at block 2,224,763. Verification transcript
-                // (DNS3 getblockhash output) is archived in the v6.2.6.0 release
-                // notes on bootstrap.cryptographic-triangles.org.
-//
-// Note: the gap from 2,219,922 to 2,222,900 is 2,978 blocks (larger than the
-                // 1,000-block standard spacing), because block 2,220,000 etc. were
-                // not indexed in DNS3's local block index when this release was
-                // prepared. The 2,222,900+ pins restore the 1,000-block spacing
-                // guarantee from that point to the live tip.
-                { 2222900, uint256("0xe104c29d6a6ff983d9a02a9854a86c221a1f400f0116cb255cee2b8d5c7ced9f")},
-                { 2223000, uint256("0x41926ba6dc9147e361ffd1ffc1a0357d7d7b66550ed05864d1ae103c6332371a")},
-                { 2223500, uint256("0x998e65941f200359ca0c1f53ea128c27f83111e8bbb1db38b7ed2ed7a48b8e32")},
-                { 2223700, uint256("0x97d3a70d258c34429c15b430e654fa1270e4de635ecec3c72ace92a0d04679c3")},
-                { 2224000, uint256("0x4dddc0b555266a1207fef70af17db9a7b14ab5e1d7cf27882ea35cc77923841f")},
-                { 2224500, uint256("0xe0fea543829dd0e8c02b7c657468cff775c7993658c16c1feaf1418b4080ba27")},
-                { 2224700, uint256("0x2a8ea5ef954adb707286bc468fdf43d8d99d23a1d15cf4f17a35d58dd51b0944")},
-                { 2224750, uint256("0x0f117fe05befb6d8a93c6e45bc3b3d48889208e2785ba6a3d723c8ad7c9d649f")},
-                { 2224763, uint256("0x9d3575ac5428e64911e698ba0a8f773954b17b214a044d4b244fa2ec83c06674")}, // live tip
+                // Operator rollback canonical (cycle-32, 2026-08-06): the chain was
+                // rolled back to height 2,172,037 (hash 52b12f09...) so the entire
+                // span 2,172,038..2,224,763 no longer exists on the canonical chain.
+                // All pins from 2,205,000..2,224,763 have been REMOVED from the map
+                // (NOT preserved). Their block hashes are not in the canonical chain,
+                // so leaving them as map entries would let GetTotalBlocksEstimate()
+                // return 2,214,400 — keeping the daemon permanently in IBD because
+                // nBestHeight (2,172,037) < 2,214,400. With the operator-rollback
+                // pin at 2,172,037 as the new highest entry, GetTotalBlocksEstimate()
+                // and GetLastCheckpointHeight() both return 2,172,037, so a node
+                // that reaches 2,172,037 exits IBD cleanly. The pin at 17,650
+                // (line above) remains as the lowest anchored finality reference.
+                // Operator-rollback finality pin (cycle-33, 2026-08-06): the new
+                // canonical tip after the operator rollback to 2,172,037. Hash
+                // verified against all 4 fleet nodes (DNS2/DNS3/Hetzner/SAMI-PC)
+                // at canonical tip 2,172,037. This is now the highest entry in
+                // mapCheckpoints, so GetTotalBlocksEstimate() returns 2,172,037 and
+                // IsInitialBlockDownload() returns false once a node reaches
+                // 2,172,037. Closes the unchecked span between the prior highest
+                // pin (17,650) and the new canonical tip for any future
+                // fresh-from-zero sync.
+                { 2172037, uint256("0x52b12f0970191505d9982449875822b78f075d7d76307abed45e7132f5fa2f16")}, // new canonical tip
             };
 
     // Published UTXO snapshot file SHA256, keyed by snapshot height.
@@ -89,12 +68,17 @@ namespace Checkpoints
     // here. The corresponding (height, blockhash) must already exist in
     // mapCheckpoints / mapCheckpointsTestnet.
     static std::map<int, uint256> mapSnapshotHashes = {
-        { 2206004, uint256("0x1419282dae817315ee1b955543f6248233fe5800f5e8488734a0ece5bd6781ea")},
-        { 2219922, uint256("0x6dd8d782a04bb8dc4ccd5e88a4bc7726fe26bdebaed96b79242de1e2949b6ee6")},
-        // Live-tip snapshot (v6.2.6.0). Generated from DNS3 (Samihost) at the
-        // canonical tip 2,224,763, blockhash 9d3575ac...06674. Verified against
-        // the canonical chain on 2026-08-04.
-        { 2224763, uint256("0xa7ea62ad4e158faf07973e5cd1539c1895154c4e28685a3eb7af458a001037b7")},
+        // Historical snapshots preserved as documentation only. The canonical
+        // chain is now at 2,172,037 (operator rollback 2026-08-06). Any wallet
+        // recovering from these old snapshots would also need to bypass the
+        // chain-state checks via the rollback recipe (see
+        // genesis-block-pow-exemption SKILL.md "SAMI-PC wallet recovery recipe"),
+        // which uses the local-file path (utxo-snapshot.bin) with
+        // -acceptanylocalsnapshot=1 — that path does NOT enforce the SHA gate.
+        // The compiled map below must contain only the canonical snapshot so
+        // GetBestSnapshotHeight() returns 2,172,037 and DownloadUtxoSnapshot
+        // selects the canonical file from bootstrap.cryptographic-triangles.org.
+        { 2172037, uint256("0xfc3b2035525564156f2489e8929e132b75e9be285d9129ad21bc89ecdc4c7977")}, // canonical
     };
 
     static std::map<int, uint256> mapSnapshotHashesTestnet = {

src/clientversion.h

@@ -9,7 +9,7 @@
 #define CLIENT_VERSION_MAJOR       6
 #define CLIENT_VERSION_MINOR       2
 #define CLIENT_VERSION_REVISION    6
-#define CLIENT_VERSION_BUILD       1
+#define CLIENT_VERSION_BUILD       4
 
 // Converts the parameter X to a string after macro replacement on X has been performed.
 // Don't merge these into one macro!

src/i2p/i2p_embedded.cpp

@@ -401,16 +401,42 @@ bool CI2PEmbedded::Start(int socks, int sam, int server)
 {
     if (running.load()) return true;
 
+    // ----------------------------------------------------------------
+    // PHASE 0: validate input BEFORE any state mutation.
+    // If validation fails, we must leave the system in a clean state
+    // (running=false, no i2p data dir side effects, no InitI2P call).
+    // ----------------------------------------------------------------
+    if (socks < 1 || socks > 65535) {
+        lastError = strprintf("SOCKS proxy port %d out of range (1-65535)", socks);
+        return false;
+    }
+    if (sam < 1 || sam > 65535) {
+        lastError = strprintf("SAM bridge port %d out of range (1-65535)", sam);
+        return false;
+    }
+    if (server < 0 || server > 65535) {
+        lastError = strprintf("server tunnel port %d out of range (0-65535, 0=disable)", server);
+        return false;
+    }
+
     lastError.clear();
     socksPort = socks;
     samPort = sam;
     serverPort = server;
-    i2pHostname.clear();
+    {
+        std::lock_guard<std::mutex> lock(hostnameMutex);
+        i2pHostname.clear();
+    }
 
     // Prepare i2pd data directory under the wallet's data dir
     i2pDataDir = (::GetDataDir() / "i2p_data").string();
-    fs::create_directories(i2pDataDir);
-    fs::permissions(i2pDataDir, fs::perms::owner_all, fs::perm_options::replace);
+    try {
+        fs::create_directories(i2pDataDir);
+        fs::permissions(i2pDataDir, fs::perms::owner_all, fs::perm_options::replace);
+    } catch (const fs::filesystem_error& e) {
+        lastError = strprintf("Cannot create i2p data dir %s: %s", i2pDataDir.c_str(), e.what());
+        return false;
+    }
 
     printf("Embedded I2P: starting i2pd router...\n");
 
@@ -448,6 +474,13 @@ bool CI2PEmbedded::Start(int socks, int sam, int server)
         conf << "address = 127.0.0.1\n";
         conf << "port = " << samPort << "\n";
         conf << "\n";
+        // Disable HTTP proxy (port 4444). Cycle-13 fix: the HTTPProxy runs by
+        // default in i2pd 2.60.0 and any HTTP request to its port causes a
+        // nullptr deref in i2p::i18n::Locale::GetString. Conf is dead code in
+        // the embedded library path; SetOption in InitI2P is the real override.
+        conf << "[httpproxy]\n";
+        conf << "enabled = false\n";
+        conf << "\n";
         // Disable HTTP webconsole (not needed for embedded use)
         conf << "[http]\n";
         conf << "enabled = false\n";
@@ -470,20 +503,29 @@ bool CI2PEmbedded::Start(int socks, int sam, int server)
     if (serverPort > 0) {
         fs::path tunnelConfPath = fs::path(i2pDataDir) / "tunnels.conf";
         std::ofstream tunnelConf(tunnelConfPath.string());
-        if (tunnelConf.is_open()) {
-            tunnelConf << "# Auto-generated by Triangles embedded I2P\n";
-            tunnelConf << "[triangles-p2p]\n";
-            tunnelConf << "type = server\n";
-            tunnelConf << "host = 127.0.0.1\n";
-            tunnelConf << "port = " << serverPort << "\n";
-            tunnelConf << "keys = triangles-p2p-keys.dat\n";
-            tunnelConf << "inbound.length = 3\n";
-            tunnelConf << "outbound.length = 3\n";
-            tunnelConf << "inbound.quantity = 5\n";
-            tunnelConf << "outbound.quantity = 5\n";
-            tunnelConf.close();
-            printf("Embedded I2P: server tunnel configured on port %d\n", serverPort);
+        if (!tunnelConf.is_open()) {
+            lastError = strprintf("Failed to write %s for server tunnel configuration",
+                                  tunnelConfPath.string().c_str());
+            printf("ERROR: %s\n", lastError.c_str());
+            return false;
         }
+        tunnelConf << "# Auto-generated by Triangles embedded I2P\n";
+        tunnelConf << "[triangles-p2p]\n";
+        tunnelConf << "type = server\n";
+        tunnelConf << "host = 127.0.0.1\n";
+        tunnelConf << "port = " << serverPort << "\n";
+        tunnelConf << "keys = triangles-p2p-keys.dat\n";
+        tunnelConf << "inbound.length = 3\n";
+        tunnelConf << "outbound.length = 3\n";
+        tunnelConf << "inbound.quantity = 5\n";
+        tunnelConf << "outbound.quantity = 5\n";
+        tunnelConf.close();
+        if (tunnelConf.fail()) {
+            lastError = strprintf("Write failed for %s", tunnelConfPath.string().c_str());
+            printf("ERROR: %s\n", lastError.c_str());
+            return false;
+        }
+        printf("Embedded I2P: server tunnel configured on port %d\n", serverPort);
     }
 
     // Build argv for i2pd initialization. Pass --datadir and --conf on the
@@ -501,14 +543,36 @@ bool CI2PEmbedded::Start(int socks, int sam, int server)
         argvPtrs.push_back(&s[0]);
     argvPtrs.push_back(nullptr);
 
+    // The whole post-InitI2P section is wrapped in try/catch so that ANY
+    // failure after i2pd is initialized triggers TerminateI2P. Without this
+    // an exception from SetOption or std::thread construction would leave
+    // running=true but with no router thread to clean up — a leaked i2pd.
     try {
         // ----------------------------------------------------------------
-        // Phase 1 (synchronous, < 1s): config parse, crypto, router context
+        // Phase 1 (synchronous, < 1s): config parse, crypto, router context.
+        // InitI2P is wrapped in try/catch so a partial-init failure does
+        // not leave i2pd in a half-initialized state with running=true.
         // ----------------------------------------------------------------
-        i2p::api::InitI2P((int)(argvPtrs.size() - 1), argvPtrs.data(), "triangles-i2pd");
+        try {
+            i2p::api::InitI2P((int)(argvPtrs.size() - 1), argvPtrs.data(), "triangles-i2pd");
+        } catch (const std::exception& e) {
+            lastError = strprintf("InitI2P failed: %s", e.what());
+            // Best-effort cleanup: i2pd's InitI2P may have partially
+            // initialized global state. TerminateI2P is a no-op if no
+            // init happened; it cleans up otherwise.
+            try { i2p::api::TerminateI2P(); } catch (...) {}
+            return false;
+        } catch (...) {
+            lastError = "InitI2P failed: unknown exception";
+            try { i2p::api::TerminateI2P(); } catch (...) {}
+            return false;
+        }
         fflush(stdout);
 
         // Mark running immediately so Qt UI shows I2P as active.
+        // From this point on, any exception thrown by the code below is
+        // caught by the outer try/catch, which calls TerminateI2P to
+        // release the partially-initialized i2pd state.
         running.store(true);
 
         // ----------------------------------------------------------------
@@ -548,17 +612,11 @@ bool CI2PEmbedded::Start(int socks, int sam, int server)
         // but BEFORE the background thread calls i2p::client::context.Start
         // which calls ReadSocksProxy + ReadSAMBridge. SetOption calls
         // notify() internally, so the new values are visible to GetOption.
+        //
+        // NOTE: SOCKS/SAM port range validation happens in Start() Phase 0
+        // before any state mutation, so by this point socksPort and samPort
+        // are already known to be 1..65535. No re-validation needed here.
         // ----------------------------------------------------------------
-        if (socksPort < 1 || socksPort > 65535) {
-            lastError = strprintf("SOCKS proxy port %d out of range (1-65535)",
-                                  socksPort);
-            return false;
-        }
-        if (samPort < 1 || samPort > 65535) {
-            lastError = strprintf("SAM bridge port %d out of range (1-65535)",
-                                  samPort);
-            return false;
-        }
         printf("Embedded I2P: overriding socksproxy.port=%d sam.port=%d via SetOption\n",
                socksPort, samPort);
         fflush(stdout);
@@ -570,7 +628,14 @@ bool CI2PEmbedded::Start(int socks, int sam, int server)
             bool samEnabled = true;
             std::string samAddr = "127.0.0.1";
             uint16_t samPortVal = (uint16_t)samPort;
-            bool httpEnabled = false;
+            // Cycle-13 fix: HTTPProxy runs by default in i2pd 2.60.0 on
+            // port 4444 and any inbound HTTP request crashes the daemon via
+            // nullptr deref in i2p::i18n::Locale::GetString (m_Language is
+            // never initialized). The previous SetOption("http.enabled",...)
+            // targeted the i2pd WEBCONSOLE, not the HTTPProxy. Correct key
+            // is "httpproxy.enabled".
+            bool httpproxyEnabled = false;
+            bool httpWebconsoleEnabled = false;
             bool i2pcontrolEnabled = false;
             bool bobEnabled = false;
 
@@ -581,7 +646,9 @@ bool CI2PEmbedded::Start(int socks, int sam, int server)
             i2p::config::SetOption("sam.enabled", samEnabled);
             i2p::config::SetOption("sam.address", samAddr);
             i2p::config::SetOption("sam.port", samPortVal);
-            i2p::config::SetOption("http.enabled", httpEnabled);
+            // Cycle-13 fix: was "http.enabled" which targeted webconsole.
+            i2p::config::SetOption("httpproxy.enabled", httpproxyEnabled);
+            i2p::config::SetOption("http.enabled", httpWebconsoleEnabled);
             i2p::config::SetOption("i2pcontrol.enabled", i2pcontrolEnabled);
             i2p::config::SetOption("bob.enabled", bobEnabled);
         }
@@ -665,19 +732,35 @@ bool CI2PEmbedded::Start(int socks, int sam, int server)
                     }
                 }
 
-                // Populate .b32.i2p address
-                try {
-                    auto identHash = i2p::context.GetRouterInfo().GetIdentHash();
-                    i2pHostname = identHash.ToBase32() + ".b32.i2p";
-                    printf("Embedded I2P: router address = %s\n", i2pHostname.c_str());
-                } catch (...) {
-                    printf("Embedded I2P: .b32.i2p address not yet available, Qt timer will retry\n");
-                }
+                // ----------------------------------------------------------------
+                // Populate .b32.i2p address — use the SERVER TUNNEL destination,
+                // NOT the embedded router identity. Delegates to
+                // DiscoverServerTunnelDestination() which is also callable
+                // from GetI2PAddress() so the Qt timerI2P retry path picks
+                // up the result once the tunnel registers.
+                // ----------------------------------------------------------------
+                DiscoverServerTunnelDestination();
                 fflush(stdout);
 
             } catch (const std::exception& e) {
+                // Background init failure: i2pd router context may be partially
+                // alive (transports listening, netDb half-built). Tear it down,
+                // reset running, and surface the error in lastError so callers
+                // can see the failure rather than seeing running=true forever.
                 printf("ERROR: Embedded I2P background init failed: %s\n", e.what());
                 fflush(stdout);
+                lastError = std::string("i2pd background init failed: ") + e.what();
+                try { i2p::api::TerminateI2P(); } catch (...) {}
+                running.store(false);
+            } catch (...) {
+                // Catch-all: any non-std::exception (e.g. structured exception
+                // on Windows) would otherwise invoke std::terminate, killing
+                // the daemon with no useful diagnostic.
+                printf("ERROR: Embedded I2P background init failed: unknown exception\n");
+                fflush(stdout);
+                lastError = "i2pd background init failed: unknown exception";
+                try { i2p::api::TerminateI2P(); } catch (...) {}
+                running.store(false);
             }
         });
 
@@ -689,6 +772,16 @@ bool CI2PEmbedded::Start(int socks, int sam, int server)
     } catch (const std::exception& e) {
         lastError = std::string("i2pd initialization failed: ") + e.what();
         printf("ERROR: Embedded I2P startup failed: %s\n", e.what());
+        // i2pd may be partially or fully initialized by the time we got here.
+        // TerminateI2P is a no-op if InitI2P never ran; otherwise it cleans
+        // up router context, transports, and netDb.
+        try { i2p::api::TerminateI2P(); } catch (...) {}
+        running.store(false);
+        return false;
+    } catch (...) {
+        lastError = "i2pd initialization failed: unknown exception";
+        printf("ERROR: Embedded I2P startup failed: unknown exception\n");
+        try { i2p::api::TerminateI2P(); } catch (...) {}
         running.store(false);
         return false;
     }
@@ -736,6 +829,160 @@ void CI2PEmbedded::Stop()
     running.store(false);
 }
 
+// ----------------------------------------------------------------
+// CI2PEmbedded::DiscoverServerTunnelDestination
+//
+// Reads triangles-p2p-keys.dat (binary PrivateKeys blob) and looks for
+// a matching entry in i2p::client::context.GetServerTunnels(). On
+// match, sets i2pHostname to the corresponding ".b32.i2p" address.
+// On no match (or serverPort==0, or read failure), leaves i2pHostname
+// empty. Idempotent and safe to call repeatedly from the Qt timerI2P
+// path (qt/trianglesgui.cpp:384-387, default 5s interval).
+//
+// Why fail-closed: publishing the keys-file hash while the tunnel is
+// not yet registered would mean advertising a destination with no
+// published LeaseSet → peers hit SOCKS code 4 / "LeaseSet not found"
+// on the floodfill network. Empty hostname → no wrong-identity
+// connectivity. The Qt timer keeps retrying until the tunnel comes up.
+// ----------------------------------------------------------------
+void CI2PEmbedded::DiscoverServerTunnelDestination()
+{
+    std::lock_guard<std::mutex> lock(hostnameMutex);
+
+    if (serverPort == 0) {
+        // No P2P server tunnel configured. This is the -nolisten / no
+        // -i2phsport case (pure outbound SOCKS I2P, no inbound service).
+        if (!i2pHostname.empty()) {
+            printf("Embedded I2P: serverPort=0, clearing previously "
+                   "discovered destination\n");
+            i2pHostname.clear();
+        }
+        return;
+    }
+
+    bool advertised = false;
+    std::string serverKeysPath = (fs::path(i2pDataDir) / "triangles-p2p-keys.dat").string();
+
+    // Step 1: read expected ident hash from the keys file.
+    std::string keysFileIdentB32;
+    try {
+        std::ifstream ks(serverKeysPath, std::ifstream::binary);
+        if (ks.is_open()) {
+            ks.seekg(0, std::ios::end);
+            size_t len = ks.tellg();
+            ks.seekg(0, std::ios::beg);
+            if (len == 0 || len > 65536) {
+                throw std::runtime_error("implausible keys file size: " +
+                                         std::to_string(len));
+            }
+            std::vector<uint8_t> buf(len);
+            ks.read(reinterpret_cast<char*>(buf.data()), len);
+            if (!ks) {
+                throw std::runtime_error("short read on keys file");
+            }
+            i2p::data::PrivateKeys pk;
+            if (!pk.FromBuffer(buf.data(), len)) {
+                throw std::runtime_error("PrivateKeys::FromBuffer failed");
+            }
+            auto pub = pk.GetPublic();
+            if (!pub) {
+                throw std::runtime_error("PrivateKeys::GetPublic returned null");
+            }
+            keysFileIdentB32 = pub->GetIdentHash().ToBase32();
+        } else {
+            // Quiet on retry — file-not-found is expected before the
+            // bootstrap thread writes it for the first time.
+            if (i2pHostname.empty()) {
+                // First failure: log at info level so the operator can
+                // see why the hostname is still empty.
+                printf("Embedded I2P: cannot open %s for server tunnel keys "
+                       "(will retry on next timerI2P tick)\n",
+                       serverKeysPath.c_str());
+            }
+        }
+    } catch (const std::exception& e) {
+        lastDiscoveryError = e.what();
+        printf("Embedded I2P: keys-file ident hash load failed: %s\n", e.what());
+    } catch (...) {
+        lastDiscoveryError = "unknown exception";
+        printf("Embedded I2P: keys-file ident hash load failed: unknown exception\n");
+    }
+
+    // Step 2: only publish if a LIVE registered server tunnel matches
+    // the keys-file hash. Registry membership confirms the tunnel is
+    // active; LeaseSet publication is i2pd's responsibility after that.
+    //
+    // Thread-safety: GetServerTunnels() returns a const reference to
+    // i2pd's internal m_ServerTunnels map, which has NO internal lock.
+    // VisitTunnels(true) (called from ReloadConfig / Stop) can erase
+    // entries concurrently. We make a VALUE COPY of the map (not a
+    // reference) so that iterator invalidation during the copy is a
+    // narrow read-only window, and all string comparisons run on the
+    // local snapshot with no live-map access. The copy constructor of
+    // std::map is exception-safe; if it throws (bad_alloc), the catch
+    // below handles it.
+    if (!keysFileIdentB32.empty()) {
+        try {
+            auto tunnels = i2p::client::context.GetServerTunnels(); // value copy
+            for (const auto& kv : tunnels) {
+                const auto& dest = kv.first.first;
+                if (dest.ToBase32() == keysFileIdentB32) {
+                    if (i2pHostname != keysFileIdentB32 + ".b32.i2p") {
+                        i2pHostname = keysFileIdentB32 + ".b32.i2p";
+                        lastDiscoveryError.clear(); // success — clear stale
+                        printf("Embedded I2P: server tunnel address "
+                               "(live registry) = %s\n", i2pHostname.c_str());
+                    }
+                    advertised = true;
+                    break;
+                }
+            }
+        } catch (const std::exception& e) {
+            lastDiscoveryError = e.what();
+            printf("Embedded I2P: server tunnel registry read failed: %s\n", e.what());
+        } catch (...) {
+            lastDiscoveryError = "unknown exception";
+            printf("Embedded I2P: server tunnel registry read failed: "
+                   "unknown exception\n");
+        }
+    }
+
+    if (!advertised) {
+        // Not yet in live registry. Leave empty (or clear stale value).
+        if (!i2pHostname.empty()) {
+            printf("Embedded I2P: server tunnel left live registry, "
+                   "clearing destination %s\n", i2pHostname.c_str());
+            i2pHostname.clear();
+        }
+    }
+}
+
+// CI2PEmbedded::GetI2PAddress — read the cached destination, retrying
+// discovery if empty. Called from qt/trianglesgui.cpp:1875
+// (updateI2PAddress) on every timerI2P tick.
+//
+// Threading: read-by-copy under hostnameMutex so concurrent writes by
+// the bootstrap thread cannot tear the std::string.
+std::string CI2PEmbedded::GetI2PAddress()
+{
+    bool needDiscovery = false;
+    {
+        std::lock_guard<std::mutex> lock(hostnameMutex);
+        needDiscovery = i2pHostname.empty() && running.load();
+    }
+
+    if (needDiscovery) {
+        // Tunnel may have registered since the bootstrap-thread scan.
+        // Re-scans the registry and the keys file (does file I/O); not
+        // "cheap" on retry, but bounded — single registry walk + one
+        // small file read.
+        DiscoverServerTunnelDestination();
+    }
+
+    std::lock_guard<std::mutex> lock(hostnameMutex);
+    return i2pHostname;
+}
+
 #else // !ENABLE_I2P_EMBEDDED
 
 // ========================================================================
@@ -758,6 +1005,14 @@ void CI2PEmbedded::Stop()
     running.store(false);
 }
 
+// Stubs for the new methods (header declares them unconditionally)
+void CI2PEmbedded::DiscoverServerTunnelDestination() {}
+std::string CI2PEmbedded::GetI2PAddress()
+{
+    std::lock_guard<std::mutex> lock(hostnameMutex);
+    return i2pHostname;
+}
+
 #endif // ENABLE_I2P_EMBEDDED
 
 // ========================================================================

src/i2p/i2p_embedded.h

@@ -7,6 +7,8 @@
 
 #include <string>
 #include <atomic>
+#include <mutex>
+#include <thread>
 
 // Cross-platform socket handle for SAM v3 streaming API.
 // On Windows this is the native SOCKET type; on POSIX it is int (fd).
@@ -92,12 +94,41 @@ private:
     int samPort;            // i2pd SAM bridge port (for SAM v3 protocol)
     int serverPort;         // Triangles P2P listen port (for incoming I2P connections)
     std::string i2pDataDir; // i2pd data directory (under wallet datadir)
+    // Hostname and discovery-error cache are read by the Qt UI thread
+    // (qt/trianglesgui.cpp:1875 updateI2PAddress) on every 5s timerI2P
+    // tick and written by the bootstrap thread. Mutex-guarded to avoid
+    // a C++ data race on the std::string itself.
+    mutable std::mutex hostnameMutex;
     std::string i2pHostname; // Our .b32.i2p address (available after router startup)
     std::string lastError;
     // I2P bootstrap runs in a background thread; we keep the handle so Stop()
     // can join it. (A detached thread that is still running blocks process exit.)
     std::thread routerThread;
 
+    // Server-tunnel destination discovery.
+    //
+    // Scans the live server tunnel registry (i2p::client::context
+    // ::GetServerTunnels()) for an entry whose ident hash matches the
+    // public key in triangles-p2p-keys.dat. Sets i2pHostname to the
+    // corresponding ".b32.i2p" address on success; leaves i2pHostname
+    // empty otherwise. Thread-safe: the registry scan is mutex-guarded
+    // inside libi2pd_client; we only read the resulting map.
+    //
+    // This is a no-op when serverPort == 0 (no inbound server tunnel
+    // configured — pure outbound SOCKS I2P mode).
+    //
+    // Idempotent. Called from the bootstrap thread AND from
+    // GetI2PAddress() when i2pHostname is empty, so the Qt timerI2P
+    // (qt/trianglesgui.cpp:384-387) picks up the result on its next
+    // 5s tick once the tunnel registers.
+    void DiscoverServerTunnelDestination();
+
+    // Cache the most recent discovery failure reason (parsed keys-file
+    // hash, registry-read error, etc.). Visible only to GetStartupError()
+    // callers in the header — no public accessor for lastDiscoveryError
+    // is needed today.
+    std::string lastDiscoveryError;
+
 public:
     static CI2PEmbedded* GetInstance();
 
@@ -121,8 +152,11 @@ public:
     int GetServerPort() const { return serverPort; }
     const std::string& GetDataDir() const { return i2pDataDir; }
 
-    // Get our .b32.i2p destination address
-    std::string GetI2PAddress() const { return i2pHostname; }
+    // Get our .b32.i2p destination address. Triggers a discovery retry
+    // if the hostname is empty (e.g. first attempt raced the tunnel
+    // registration). Idempotent and cheap when the hostname is already
+    // populated.
+    std::string GetI2PAddress();
     std::string GetStartupError() const { return lastError; }
     void SetStartupError(const std::string& value) { lastError = value; }
 
@@ -144,4 +178,4 @@ public:
 bool StartEmbeddedI2P();
 void StopEmbeddedI2P();
 
-#endif // TRIANGLES_I2P_EMBEDDED_H
+#endif // TRIANGLES_I2P_EMBEDDED_H

src/init.cpp

@@ -35,6 +35,7 @@
 #include <thread>
 #include <vector>
 #include <cerrno>
+#include <cstdio>
 
 // Forward declaration: InitError / InitWarning are defined further down
 // in this file but referenced by AppInit (line ~423) before the definition.
@@ -45,6 +46,12 @@ static bool InitWarning(const std::string& str);
 #include <algorithm>
 #include <openssl/crypto.h>
 
+#ifdef WIN32
+// _get_osfhandle lives in <io.h>; FlushFileBuffers / HANDLE live in <windows.h>,
+// which is transitively included via util.h on Windows builds.
+#include <io.h>
+#endif
+
 #ifndef WIN32
 #include <signal.h>
 #include <sys/file.h>
@@ -102,6 +109,49 @@ bool LockDataDirectory(const std::filesystem::path& pathLockFile)
 #endif
 }
 
+bool SyncReindexMarker(const fs::path& markerPath)
+{
+    // POSIX systems guarantee parent-directory durability via fsync(dirfd).
+    // Windows does not expose an equivalent primitive for directory metadata;
+    // `_commit` flushes the file's data to disk and the underlying NTFS
+    // journal commits the directory entry on close. Both paths below flush
+    // before close to maximise durability; Windows users get file-data
+    // durability equivalent to POSIX, with directory metadata committed by
+    // the journal.
+    FILE* marker = std::fopen(markerPath.string().c_str(), "wb");
+    if (!marker)
+        return false;
+    static const char text[] = "Reindex must complete successfully before normal startup.\n";
+    bool ok = std::fwrite(text, 1, sizeof(text) - 1, marker) == sizeof(text) - 1 &&
+              std::fflush(marker) == 0;
+#ifdef WIN32
+    // FlushFileBuffers on the file handle commits data durably to NTFS.
+    intptr_t osHandle = _get_osfhandle(_fileno(marker));
+    if (osHandle == -1 || FlushFileBuffers(reinterpret_cast<HANDLE>(osHandle)) == FALSE)
+        ok = false;
+#else
+    if (ok)
+        ok = ::fsync(fileno(marker)) == 0;
+#endif
+    if (std::fclose(marker) != 0)
+        ok = false;
+#ifdef WIN32
+    // No directory-fsync primitive on Windows. The journal commit on close
+    // (and the FlushFileBuffers above) is the strongest durability available.
+    // See comment block above.
+#else
+    if (ok)
+    {
+        int dirFd = ::open(markerPath.parent_path().string().c_str(), O_RDONLY | O_DIRECTORY);
+        if (dirFd < 0)
+            return false;
+        ok = ::fsync(dirFd) == 0;
+        ::close(dirFd);
+    }
+#endif
+    return ok;
+}
+
 #ifndef WIN32
 bool EnsureOwnerOnlyFile(const std::filesystem::path& path, std::string& error)
 {
@@ -178,95 +228,19 @@ void ExitTimeout(void* parg)
 #endif
 }
 
-// Wait up to maxWaitSec for at least minPeers peers to have reported their
-// chain height via the version handshake. Returns the median peer height, or
-// -1 if we couldn't get enough peers (timeout, no peers, all nStartingHeight=-1).
-int WaitForPeerHeights(int minPeers, int maxWaitSec)
+// Automatic recovery is intentionally non-destructive. Older builds deleted the
+// chain DB and blk0001.dat when a node lagged its peers, which could turn a
+// transient peer-height report into permanent local data loss. A privacy coin
+// must never rewrite historical chain data automatically; recovery remains an
+// explicit operator action after wallet and chain-state backups.
+// Legacy hook retained only to surface that -autorerebuild no longer mutates
+// chain state.
+static void LogAutoRebuildDisabled(int thresholdBlocks)
 {
-    const int pollIntervalMs = 500;
-    const int64_t deadline = GetTimeMillis() + (int64_t)maxWaitSec * 1000;
-
-    while (GetTimeMillis() < deadline && !fRequestShutdown) {
-        std::vector<int> heights;
-        {
-            LOCK(cs_vNodes);
-            for (CNode* pnode : vNodes) {
-                if (pnode && pnode->nStartingHeight > 0)
-                    heights.push_back(pnode->nStartingHeight);
-            }
-        }
-        if ((int)heights.size() >= minPeers) {
-            std::sort(heights.begin(), heights.end());
-            int median = heights[heights.size() / 2];
-            printf("AutoRebuild: got %zu peer heights; median=%d\n", heights.size(), median);
-            return median;
-        }
-        MilliSleep(pollIntervalMs);
+    if (thresholdBlocks > 0) {
+        printf("AutoRebuild: -autorerebuild=%d ignored; automatic chain deletion is disabled.\n",
+               thresholdBlocks);
     }
-
-    std::vector<int> heights;
-    {
-        LOCK(cs_vNodes);
-        for (CNode* pnode : vNodes) {
-            if (pnode && pnode->nStartingHeight > 0)
-                heights.push_back(pnode->nStartingHeight);
-        }
-    }
-    if (heights.empty()) {
-        printf("AutoRebuild: no peers reported heights after %ds\n", maxWaitSec);
-        return -1;
-    }
-    std::sort(heights.begin(), heights.end());
-    int median = heights[heights.size() / 2];
-    printf("AutoRebuild: timed out with %zu peers; median=%d\n", heights.size(), median);
-    return median;
-}
-
-// If -autorerebuild is set and our local chain is more than that many blocks
-// behind the median peer height, wipe the chain DB (preserving wallet.dat +
-// onion + smsg state) and request shutdown. On restart, the daemon sees no
-// chain DB and the snapshot path takes over.
-void MaybeAutoRebuild(int thresholdBlocks)
-{
-    if (thresholdBlocks <= 0)
-        return;
-
-    if (nBestHeight < 0) {
-        printf("AutoRebuild: local nBestHeight unset — skipping\n");
-        return;
-    }
-
-    printf("AutoRebuild: enabled (threshold=%d blocks). Local chain tip: %d\n",
-           thresholdBlocks, nBestHeight);
-    int medianPeer = WaitForPeerHeights(/*minPeers=*/3, /*maxWaitSec=*/60);
-    if (medianPeer <= 0) {
-        printf("AutoRebuild: could not get peer heights — skipping rebuild\n");
-        return;
-    }
-
-    int lag = medianPeer - nBestHeight;
-    printf("AutoRebuild: peer median=%d, local=%d, lag=%d\n",
-           medianPeer, nBestHeight, lag);
-
-    if (lag < thresholdBlocks) {
-        printf("AutoRebuild: lag %d < threshold %d — no rebuild needed\n",
-               lag, thresholdBlocks);
-        return;
-    }
-
-    printf("\n*** AutoRebuild: chain is %d blocks behind — wiping chain DB ***\n", lag);
-    printf("*** Preserving wallet.dat, smsgDB, onion state. ***\n");
-    printf("*** Daemon will shutdown; restart to load signed UTXO snapshot. ***\n\n");
-
-    WipeChainDataDir();
-
-    fs::path blkPath = GetDataDir() / "blk0001.dat";
-    if (fs::exists(blkPath)) {
-        fs::remove(blkPath);
-        printf("AutoRebuild: removed stale %s\n", blkPath.string().c_str());
-    }
-
-    StartShutdown();
 }
 
 void StartShutdown()
@@ -655,7 +629,7 @@ std::string HelpMessage()
         "  -onionseed             " + _("Find peers using .onion seeds (default: 1 unless -connect)") + "\n" +
         "  -seedurl=<host>        " + _("HTTP seed list host (default: seeds.cryptographic-triangles.org)") + "\n" +
         "  -noseedurl             " + _("Disable HTTP seed list fetch on startup") + "\n" +
-        "  -autorerebuild=<n>     " + _("If our chain is more than <n> blocks behind peers, wipe chain DB and shutdown for clean restart (default: 0=disabled)") + "\n" +
+        "  -autorerebuild=<n>     " + _("Deprecated compatibility option; automatic chain deletion is disabled") + "\n" +
         "  -banscore=<n>          " + _("Threshold for disconnecting misbehaving peers (default: 100)") + "\n" +
         "  -bantime=<n>           " + _("Number of seconds to keep misbehaving peers from reconnecting (default: 86400)") + "\n" +
         "  -par=<n>               " + _("Set the number of script verification threads (default: auto, 0 = auto, 1 = single-threaded)") + "\n" +
@@ -707,7 +681,8 @@ std::string HelpMessage()
         "  -checkblocks=<n>       " + _("How many blocks to check at startup (default: 2500, 0 = all)") + "\n" +
         "  -checklevel=<n>        " + _("How thorough the block verification is (0-6, default: 1)") + "\n" +
         "  -loadblock=<file>      " + _("Imports blocks from external blk000?.dat file") + "\n" +
-        "  -rebuildutxo           " + _("Rebuild UTXO set from full block chain (slow, for recovery)") + "\n" +
+        "  -reindex              " + _("Rebuild the derived chain database from the existing blk0001.dat without modifying the raw block file") + "\n" +
+        "  -rebuildutxo          " + _("Rebuild UTXO set from full block chain (slow, for recovery)") + "\n" +
 
         "\n" + _("Block creation options:") + "\n" +
         "  -blockminsize=<n>      "   + _("Set minimum block size in bytes (default: 0)") + "\n" +
@@ -1424,22 +1399,66 @@ bool AppInit2()
     }
 
     // Handle -reindex: delete the chain DB so it gets rebuilt from the raw
-    // blk*.dat files. This recalculates money
+    // blk0001.dat file used by this storage format. This recalculates money
     // supply, tx index, and UTXO set from scratch. Backend-agnostic via
     // WipeChainDataDir(), which resolves the directory per the configured
     // -chaindb backend.
-    if (GetBoolArg("-reindex", false))
+    const bool fReindex = GetBoolArg("-reindex", false);
+    fs::path reindexMarker = GetDataDir() / "REINDEX_INCOMPLETE";
+
+    // Validate the immutable source before removing any derived state. A marker
+    // survives crashes/interruption so ordinary startup cannot trust a partial
+    // database left by an earlier recovery attempt.
+    if (fReindex)
     {
+        fs::path blkPath = GetDataDir() / "blk0001.dat";
+        if (!fs::exists(blkPath) || !fs::is_regular_file(blkPath))
+            return InitError(_("Reindex requested but blk0001.dat is missing or not a regular file"));
+        if (!SyncReindexMarker(reindexMarker))
+            return InitError(_("Cannot durably create REINDEX_INCOMPLETE marker in the data directory"));
+
         printf("Reindex requested: removing chain database...\n");
         uiInterface.InitMessage(_("Removing chain database for reindex..."));
         WipeChainDataDir();
+        if (fs::exists(GetChainDataDir()))
+            return InitError(_("Reindex could not remove the existing chain database"));
+    }
+    else if (fs::exists(reindexMarker))
+    {
+        return InitError(_("A previous reindex was interrupted. Restart with -reindex to rebuild derived chain state."));
     }
 
     uiInterface.InitMessage(_("Loading block index..."));
     printf("Loading block index...\n");
     nStart = GetTimeMillis();
-    if (!LoadBlockIndex())
+    // Normal startup loads the existing derived index. An explicit -reindex
+    // must NOT call LoadBlockIndex() first: on an empty database that routine
+    // creates and appends a new genesis record to blk0001.dat. Reindex instead
+    // rebuilds directly from the already-existing raw history, keeping the
+    // source block file byte-for-byte unchanged.
+    if (fReindex)
+    {
+        fs::path blkPath = GetDataDir() / "blk0001.dat";
+        if (!fs::exists(blkPath))
+            return InitError(_("Reindex requested but blk0001.dat is missing"));
+
+        printf("Reindex: rebuilding chain database from existing %s (raw block file will not be modified)\n",
+               blkPath.string().c_str());
+        uiInterface.InitMessage(_("Reindexing blocks from blk0001.dat..."));
+        int64_t nReindexStart = GetTimeMillis();
+        if (!FastImportBlockFile())
+            return InitError(_("Reindex failed while rebuilding from blk0001.dat"));
+        StartupPerfLog("reindex_fast_import", GetTimeMillis() - nReindexStart,
+                       strprintf("bestheight=%d indexsize=%" PRIszu,
+                                 nBestHeight, mapBlockIndex.size()));
+        std::error_code markerError;
+        if (!fs::remove(reindexMarker, markerError) || markerError)
+            return InitError(_("Reindex completed but REINDEX_INCOMPLETE marker could not be removed"));
+    }
+    else if (!LoadBlockIndex())
+    {
         return InitError(_("Error loading blkindex.dat"));
+    }
 
     // pindexLastHardenedCheckpoint is initialized from the hardened checkpoint
     // map on startup, BEFORE the daemon opens any peer connections or
@@ -1581,16 +1600,12 @@ bool AppInit2()
         uiInterface.InitMessage(_("UTXO rebuild complete"));
     }
 
-    // AutoRebuild: if -autorerebuild is set and we are behind peers, wipe chain DB
-    // and shutdown for clean restart.
-    MaybeAutoRebuild(GetArg("-autorerebuild", 0));
-    if (fRequestShutdown) {
-        printf("AutoRebuild: shutdown requested before chain load complete\n");
-        return false;
-    }
+    // Keep the legacy option parse for compatibility, but automatic recovery is
+    // diagnostic-only and never removes chain data.
+    LogAutoRebuildDisabled(GetArg("-autorerebuild", 0));
 
-    // Block index loaded. With fast-import removed, the only supported sync path
-    // is the UTXO snapshot (auto-downloaded from bootstrap or placed manually in datadir).
+    // Block index loaded. Normal bootstrap uses the UTXO snapshot; explicit
+    // -reindex is the operator-only recovery path from local blk0001.dat.
 
     // as LoadBlockIndex can take several minutes, it's possible the user
     // requested to kill triangles-qt during the last operation. If so, exit.

src/main.cpp

@@ -27,6 +27,7 @@
 #include <memory>
 #include <filesystem>
 #include <fstream>
+#include <limits>
 
 
 using namespace std;
@@ -118,12 +119,12 @@ void ThreadForkDetector(void*)
             printf("*** Possible fork or sync stall. Check peers: 'getpeerinfo' and chain: 'getblockhash %d' ***\n",
                    nOurHeight);
 
-            // If severe lag persists, suggest auto-rebuild
-            if (lag >= threshold * 3 && GetBoolArg("-autorerebuild", 0) > 0)
+            // Severe lag is diagnostic only. Recovery must be explicitly
+            // initiated by an operator after backups; never request an
+            // automatic shutdown that could lead to chain-state deletion.
+            if (lag >= threshold * 3 && GetBoolArg("-autorerebuild", false))
             {
-                printf("*** FORK DETECTOR: lag %d >= %d, triggering AutoRebuild ***\n",
-                       lag, threshold * 3);
-                StartShutdown();
+                printf("*** FORK DETECTOR: automatic rebuild is disabled; operator review required ***\n");
             }
         }
 
@@ -2666,19 +2667,25 @@ bool static Reorganize(CTxDBBase& txdb, CBlockIndex* pindexNew)
     // the pointer is NULL. In that state we still know the *height* of
     // the checkpoint from the compiled map directly — every node built
     // from the same binary sees the same value — and we use it as the
-    // fail-closed floor. Without this second path, an IBD-time reorg
-    // attempt below the compiled checkpoint height would silently slip
-    // through the guard.
+    // fail-closed floor.
+    //
+    // Boundary: reject only when pfork->nHeight < nHardenedCheckpointHeight.
+    // A reorg whose fork point EQUALS the checkpoint height preserves the
+    // checkpoint block (which both chains share) and only replaces blocks
+    // AFTER the checkpoint. If the new chain has higher trust, it should win
+    // per the standard trust-vs-snapshot fork-selection rule. Rejecting such
+    // a reorg would cause honest nodes that observed different height-2,172,038
+    // blocks to remain split forever even when they agree on the checkpoint.
     int nHardenedCheckpointHeight = -1;
     if (pindexLastHardenedCheckpoint)
         nHardenedCheckpointHeight = pindexLastHardenedCheckpoint->nHeight;
     else
         nHardenedCheckpointHeight = Checkpoints::GetLastCheckpointHeight();
-    if (nHardenedCheckpointHeight >= 0 && pfork->nHeight <= nHardenedCheckpointHeight)
+    if (nHardenedCheckpointHeight >= 0 && pfork->nHeight < nHardenedCheckpointHeight)
     {
-        printf("REORGANIZE: REJECTED — fork point %d is at or below shared hardened checkpoint %d\n",
+        printf("REORGANIZE: REJECTED — fork point %d is below shared hardened checkpoint %d\n",
             pfork->nHeight, nHardenedCheckpointHeight);
-        return error("Reorganize() : fork point %d at or below shared hardened checkpoint %d",
+        return error("Reorganize() : fork point %d below shared hardened checkpoint %d",
             pfork->nHeight, nHardenedCheckpointHeight);
     }
 
@@ -4145,88 +4152,213 @@ bool LoadExternalBlockFile(FILE* fileIn)
 
 bool FastImportBlockFile()
 {
-    // Fast block import: reads blk0001.dat and builds the block index
-    // directly without re-writing block data. LevelDB writes are batched
-    // every 200K blocks for speed. Only used for trusted bootstrap data
-    // (blocks below the hardcoded checkpoint).
+    // Explicit recovery importer: read the single raw block file used by this
+    // storage format and reconstruct all derived chain state without writing
+    // to blk0001.dat. The caller gates this behind -reindex.
 
     fs::path blkPath = GetDataDir() / "blk0001.dat";
     if (!fs::exists(blkPath))
         return false;
 
+    // LoadBlockIndex normally initializes these before opening the database.
+    // Reindex bypasses its genesis-creation path, so initialize the same
+    // network-specific framing and consensus parameters here.
+    if (fTestNet)
+    {
+        pchMessageStart[0] = 0x6f;
+        pchMessageStart[1] = 0x3e;
+        pchMessageStart[2] = 0x04;
+        pchMessageStart[3] = 0x13;
+        bnProofOfStakeLimit = bnProofOfStakeLimitTestNet;
+        bnProofOfWorkLimit = bnProofOfWorkLimitTestNet;
+        nStakeMinAge = 10 * 60;
+        nStakeMaxAge = 30 * 60;
+        nModifierInterval = 60;
+        nCoinbaseMaturity = 10;
+        nTargetSpacing = 60;
+    }
+
     printf("FastImportBlockFile: starting from %s\n", blkPath.string().c_str());
     int64_t nStart = GetTimeMillis();
 
     FILE* fileIn = fopen(blkPath.string().c_str(), "rb");
     if (!fileIn)
         return false;
+    std::unique_ptr<FILE, int(*)(FILE*)> fileGuard(fileIn, &fclose);
 
     // Get file size for progress
-    fseek(fileIn, 0, SEEK_END);
+    if (fseek(fileIn, 0, SEEK_END) != 0)
+        return error("FastImportBlockFile: cannot seek to end of blk0001.dat");
     int64_t nFileSize = ftell(fileIn);
-    fseek(fileIn, 0, SEEK_SET);
+    if (nFileSize <= 0 || nFileSize > (int64_t)std::numeric_limits<unsigned int>::max() ||
+        fseek(fileIn, 0, SEEK_SET) != 0)
+        return error("FastImportBlockFile: blk0001.dat size is invalid or exceeds the 32-bit disk-position format");
 
     int nLoaded = 0;
-    int64_t nLastProgressReport = 0;
+    int nRootBlocks = 0;
+    int64_t nLastRecordEnd = 0;
+    const uint256 expectedGenesis = fTestNet ? hashGenesisBlockTestNet : hashGenesisBlockOfficial;
 
     {
         LOCK(cs_main);
-        CAutoFile blkdat(fileIn, SER_DISK, CLIENT_VERSION);
 
-        auto txdb_holder = MakeChainDB(); CTxDBBase& txdb = *txdb_holder;
-        txdb.TxnBegin();
+        auto txdb_holder = MakeChainDB("cr+"); CTxDBBase& txdb = *txdb_holder;
+        if (!txdb.TxnBegin())
+            return error("FastImportBlockFile: failed to begin database transaction");
 
-        unsigned int nPos = 0;
-        while (nPos != (unsigned int)-1 && blkdat.good() && !fRequestShutdown)
+        try
         {
-            // Find message start bytes (same scan as LoadExternalBlockFile)
-            unsigned char pchData[65536];
-            do {
-                fseek(blkdat, nPos, SEEK_SET);
-                int nRead = fread(pchData, 1, sizeof(pchData), blkdat);
-                if (nRead <= 8)
-                {
-                    nPos = (unsigned int)-1;
-                    break;
-                }
-                void* nFind = memchr(pchData, pchMessageStart[0], nRead+1-sizeof(pchMessageStart));
-                if (nFind)
-                {
-                    if (memcmp(nFind, pchMessageStart, sizeof(pchMessageStart))==0)
-                    {
-                        nPos += ((unsigned char*)nFind - pchData) + sizeof(pchMessageStart);
-                        break;
-                    }
-                    nPos += ((unsigned char*)nFind - pchData) + 1;
-                }
-                else
-                    nPos += sizeof(pchData) - sizeof(pchMessageStart) + 1;
-            } while(!fRequestShutdown);
+            // The entire import runs inside this try block. The catch below
+            // guarantees the in-flight transaction is explicitly aborted on
+            // any exception (allocation, database, validation, or otherwise)
+            // before propagating, so a partial commit cannot leak even if the
+            // inner error paths miss a TxnAbort. Each inner error path also
+            // aborts explicitly for clarity.
 
-            if (nPos == (unsigned int)-1)
-                break;
-
-            fseek(blkdat, nPos, SEEK_SET);
-            unsigned int nSize;
-            blkdat >> nSize;
-
-            if (nSize == 0 || nSize > MAX_BLOCK_SIZE)
+            unsigned int nPos = 0;
+            while ((int64_t)nPos < nFileSize && !fRequestShutdown)
+        {
+            // Strict contiguous framing: every record must begin exactly at
+            // nPos with network magic + declared payload size. Do not scan
+            // forward through garbage; recovery must prove the whole file.
+            if (nFileSize - nPos < (int64_t)(sizeof(pchMessageStart) + sizeof(uint32_t)))
             {
-                nPos += 4 + nSize;
-                continue;
+                txdb.TxnAbort();
+                return error("FastImportBlockFile: truncated record header at file offset %u", nPos);
+            }
+            unsigned char recordMagic[sizeof(pchMessageStart)];
+            if (fseek(fileIn, nPos, SEEK_SET) != 0 ||
+                fread(recordMagic, 1, sizeof(recordMagic), fileIn) != sizeof(recordMagic) ||
+                memcmp(recordMagic, pchMessageStart, sizeof(recordMagic)) != 0)
+            {
+                txdb.TxnAbort();
+                return error("FastImportBlockFile: invalid record magic at file offset %u", nPos);
             }
 
-            // nBlockPos = file position where the block data starts
-            // (after 4-byte message start + 4-byte size)
-            unsigned int nBlockPos = nPos + 4;
+            uint32_t nSize = 0;
+            if (fread(&nSize, sizeof(nSize), 1, fileIn) != 1)
+            {
+                txdb.TxnAbort();
+                return error("FastImportBlockFile: cannot read block size at file offset %u", nPos);
+            }
+            if (nSize == 0 || nSize > MAX_BLOCK_SIZE)
+            {
+                txdb.TxnAbort();
+                return error("FastImportBlockFile: invalid block size %u at file offset %u", nSize, nPos);
+            }
+            const int64_t payloadPos = (int64_t)nPos + sizeof(pchMessageStart) + sizeof(nSize);
+            if (payloadPos + nSize > nFileSize)
+            {
+                txdb.TxnAbort();
+                return error("FastImportBlockFile: truncated block record at file offset %u", nPos);
+            }
 
+            std::vector<char> payload(nSize);
+            if (fread(payload.data(), 1, nSize, fileIn) != nSize)
+            {
+                txdb.TxnAbort();
+                return error("FastImportBlockFile: short payload read at file offset %u", nPos);
+            }
+
+            const unsigned int nBlockPos = (unsigned int)payloadPos;
             CBlock block;
-            blkdat >> block;
+            try
+            {
+                CDataStream record(payload.data(), payload.data() + payload.size(),
+                                   SER_DISK, CLIENT_VERSION);
+                record >> block;
+                if (!record.empty())
+                {
+                    txdb.TxnAbort();
+                    return error("FastImportBlockFile: block payload has %" PRIszu " trailing bytes at file offset %u",
+                                 record.size(), nPos);
+                }
+            }
+            catch (const std::exception& e)
+            {
+                txdb.TxnAbort();
+                return error("FastImportBlockFile: malformed block payload at file offset %u: %s",
+                             nPos, e.what());
+            }
+            catch (...)
+            {
+                txdb.TxnAbort();
+                return error("FastImportBlockFile: unknown deserialization failure at file offset %u",
+                             nPos);
+            }
+
+            const unsigned int nRecordEnd = (unsigned int)(payloadPos + nSize);
+
+            // Reindex is optimized for trusted local history but must still
+            // apply every context-free block/transaction invariant before it
+            // can write derived state. Context-dependent chain validity is
+            // anchored below by exact genesis, parent continuity, cumulative
+            // trust selection, and all compiled hardened checkpoints.
+            //
+            // PoS block-signature verification follows the runtime rule:
+            //   - blocks above the newest compiled checkpoint must be
+            //     individually signed and chain-trust valid;
+            //   - blocks at or below the newest compiled checkpoint are
+            //     covered by the historical assume-valid fast path, which
+            //     is the same rule the daemon uses at runtime. We must NOT
+            //     apply the per-block signature check unconditionally,
+            //     because that policy change was deliberately added in
+            //     v6.x to prevent chain splits over the pre-checkpoint era.
+            if (!block.CheckBlock(true, true, false))
+            {
+                txdb.TxnAbort();
+                return error("FastImportBlockFile: block failed context-free validation at file offset %u",
+                             nPos);
+            }
+            if (block.IsProofOfStake() && pindexBest->nHeight > Checkpoints::GetLastCheckpointHeight() &&
+                !block.CheckBlockSignature())
+            {
+                txdb.TxnAbort();
+                return error("FastImportBlockFile: post-checkpoint block signature failure at file offset %u",
+                             nPos);
+            }
 
             uint256 hash = block.GetHash();
+            if (block.hashPrevBlock == 0)
+            {
+                // The expected network genesis is the very first record in the
+                // file (offset 0). The runtime rule is "blocks whose parent is
+                // zero are only the genesis", and any other record with a zero
+                // parent would corrupt the active chain, so reject anything
+                // that hashes to the genesis hash anywhere other than offset 0.
+                ++nRootBlocks;
+                if (hash == expectedGenesis)
+                {
+                    if (nPos != 0 || nRootBlocks != 1)
+                    {
+                        txdb.TxnAbort();
+                        return error("FastImportBlockFile: unexpected or duplicate genesis block %s at file offset %u",
+                                     hash.ToString().c_str(), nPos);
+                    }
+                }
+                else if (nPos == 0)
+                {
+                    txdb.TxnAbort();
+                    return error("FastImportBlockFile: first record is not the expected genesis block %s",
+                                 hash.ToString().c_str());
+                }
+                else
+                {
+                    // Stray root record (previous broken -reindex runs may have
+                    // appended a fresh genesis record to blk0001.dat). Skip it:
+                    // it has no parent, no chain trust, and would otherwise be
+                    // a false duplicate of genesis. Advance strictly so the
+                    // exact-file-consumed invariant still holds.
+                    nPos = nRecordEnd;
+                    nLastRecordEnd = nPos;
+                    nLoaded++;
+                    continue;
+                }
+            }
             if (mapBlockIndex.count(hash))
             {
-                nPos += 4 + nSize;
+                nPos = nRecordEnd;
+                nLastRecordEnd = nPos;
                 continue; // already indexed
             }
 
@@ -4242,6 +4374,31 @@ bool FastImportBlockFile()
                 pindexNew->pprev = miPrev->second;
                 pindexNew->nHeight = pindexNew->pprev->nHeight + 1;
             }
+            else if (block.hashPrevBlock != 0)
+            {
+                delete pindexNew;
+                txdb.TxnAbort();
+                return error("FastImportBlockFile: parent %s missing before block %s",
+                             block.hashPrevBlock.ToString().c_str(), hash.ToString().c_str());
+            }
+
+            if (!Checkpoints::CheckHardened(pindexNew->nHeight, hash))
+            {
+                const int badHeight = pindexNew->nHeight;
+                delete pindexNew;
+                txdb.TxnAbort();
+                return error("FastImportBlockFile: hardened checkpoint mismatch at height %d",
+                             badHeight);
+            }
+            if (pindexNew->nHeight > Checkpoints::GetLastCheckpointHeight() &&
+                !block.CheckBlockSignature())
+            {
+                const int badHeight = pindexNew->nHeight;
+                delete pindexNew;
+                txdb.TxnAbort();
+                return error("FastImportBlockFile: post-checkpoint block signature failure at height %d",
+                             badHeight);
+            }
 
             // Chain trust
             pindexNew->nChainTrust = (pindexNew->pprev ? pindexNew->pprev->nChainTrust : 0) + pindexNew->GetBlockTrust();
@@ -4249,32 +4406,41 @@ bool FastImportBlockFile()
             // Stake entropy bit
             pindexNew->SetStakeEntropyBit(block.GetStakeEntropyBit());
 
-            // Stake modifier (minimal for blocks far below checkpoint)
-            int nCheckpointHeight = Checkpoints::GetTotalBlocksEstimate();
-            if (pindexNew->nHeight >= nCheckpointHeight - 1000)
+            // Recompute the exact historical stake-modifier chain. Every
+            // block must participate: using placeholder zero modifiers for
+            // older blocks leaves mature wallet UTXOs unable to resolve the
+            // later modifier required by CheckStakeKernelHash(). Reindex is
+            // an explicit recovery operation, so correctness takes priority
+            // over the old shortcut's speed.
+            uint64_t nStakeModifier = 0;
+            bool fGeneratedStakeModifier = false;
+            if (!ComputeNextStakeModifier(pindexNew->pprev,
+                                          nStakeModifier,
+                                          fGeneratedStakeModifier))
             {
-                uint64_t nStakeModifier = 0;
-                bool fGeneratedStakeModifier = false;
-                ComputeNextStakeModifier(pindexNew->pprev, nStakeModifier, fGeneratedStakeModifier);
-                pindexNew->SetStakeModifier(nStakeModifier, fGeneratedStakeModifier);
-            }
-            else
-            {
-                pindexNew->SetStakeModifier(0, pindexNew->nHeight == 0);
+                delete pindexNew;
+                txdb.TxnAbort();
+                return error("FastImportBlockFile: failed to compute stake modifier for block %s",
+                             hash.ToString().c_str());
             }
+            pindexNew->SetStakeModifier(nStakeModifier, fGeneratedStakeModifier);
+
+            // Insert into mapBlockIndex and set phashBlock BEFORE calling
+            // GetStakeModifierChecksum, which calls GetBlockHash() which
+            // dereferences phashBlock. Without this ordering, phashBlock is
+            // null and the checksum call segfaults.
+            auto mi = mapBlockIndex.insert(make_pair(hash, pindexNew)).first;
+            pindexNew->phashBlock = &mi->first;
+
             pindexNew->nStakeModifierChecksum = GetStakeModifierChecksum(pindexNew);
 
             // PoS stake seen set
             if (pindexNew->IsProofOfStake())
                 setStakeSeen.insert(make_pair(pindexNew->prevoutStake, pindexNew->nStakeTime));
 
-            // Insert into mapBlockIndex
-            auto mi = mapBlockIndex.insert(make_pair(hash, pindexNew)).first;
-            pindexNew->phashBlock = &mi->first;
-
-            // Link pnext for previous block
-            if (pindexNew->pprev)
-                pindexNew->pprev->pnext = pindexNew;
+            // pnext is rebuilt after best-chain selection. File order also
+            // contains side branches, so assigning it here would let the last
+            // imported child hijack stake-modifier forward walks.
 
             // NOTE: tx-index, UTXO-set and money-supply application are
             // DEFERRED to a second pass over the active (best-trust) chain
@@ -4285,7 +4451,12 @@ bool FastImportBlockFile()
             // That was the root cause of UTXO-set / supply inflation on every
             // reindex. Here we only build the block index for all blocks so
             // best-chain selection by trust still works.
-            txdb.WriteBlockIndex(CDiskBlockIndex(pindexNew));
+            if (!txdb.WriteBlockIndex(CDiskBlockIndex(pindexNew)))
+            {
+                txdb.TxnAbort();
+                return error("FastImportBlockFile: failed to write block index %s",
+                             hash.ToString().c_str());
+            }
 
             // Update best chain
             if (pindexNew->nChainTrust > nBestChainTrust)
@@ -4303,14 +4474,27 @@ bool FastImportBlockFile()
                 pindexGenesisBlock = pindexNew;
 
             nLoaded++;
-            nPos += 4 + nSize;
+            nPos = nRecordEnd;
+            nLastRecordEnd = nPos;
 
             // Batch commit every 200K blocks for LevelDB efficiency
             if (nLoaded % 200000 == 0)
             {
-                txdb.WriteHashBestChain(hashBestChain);
-                txdb.TxnCommit();
-                txdb.TxnBegin();
+                if (!txdb.WriteHashBestChain(hashBestChain))
+                {
+                    txdb.TxnAbort();
+                    return error("FastImportBlockFile: index batch WriteHashBestChain failed after %d blocks", nLoaded);
+                }
+                if (!txdb.TxnCommit())
+                {
+                    txdb.TxnAbort();
+                    return error("FastImportBlockFile: index batch TxnCommit failed after %d blocks", nLoaded);
+                }
+                if (!txdb.TxnBegin())
+                {
+                    txdb.TxnAbort();
+                    return error("FastImportBlockFile: index batch TxnBegin failed after %d blocks", nLoaded);
+                }
             }
 
             // Report progress every 5000 blocks to keep GUI responsive.
@@ -4324,6 +4508,42 @@ bool FastImportBlockFile()
             }
         }
 
+        if (fRequestShutdown)
+        {
+            txdb.TxnAbort();
+            return error("FastImportBlockFile: interrupted after %d blocks; reindex is incomplete", nLoaded);
+        }
+        if (nRootBlocks < 1 || nLastRecordEnd != nFileSize)
+        {
+            txdb.TxnAbort();
+            return error("FastImportBlockFile: block file was not consumed exactly (roots=%d end=%" PRId64 " size=%" PRId64 ")",
+                         nRootBlocks, nLastRecordEnd, nFileSize);
+        }
+        if (!pindexBest || !pindexGenesisBlock ||
+            pindexGenesisBlock->GetBlockHash() != expectedGenesis)
+        {
+            txdb.TxnAbort();
+            return error("FastImportBlockFile: no complete active chain found");
+        }
+
+        const int requiredCheckpointHeight = Checkpoints::GetLastCheckpointHeight();
+        CBlockIndex* requiredCheckpoint = Checkpoints::GetLastCheckpoint(mapBlockIndex);
+        if (requiredCheckpointHeight < 0 || !requiredCheckpoint ||
+            requiredCheckpoint->nHeight != requiredCheckpointHeight)
+        {
+            txdb.TxnAbort();
+            return error("FastImportBlockFile: selected chain does not reach the newest compiled checkpoint at height %d",
+                         requiredCheckpointHeight);
+        }
+        CBlockIndex* checkpointAncestor = pindexBest;
+        while (checkpointAncestor && checkpointAncestor->nHeight > requiredCheckpointHeight)
+            checkpointAncestor = checkpointAncestor->pprev;
+        if (checkpointAncestor != requiredCheckpoint)
+        {
+            txdb.TxnAbort();
+            return error("FastImportBlockFile: newest compiled checkpoint is not on selected active chain");
+        }
+
         // ---- Pass 2: apply tx-index, UTXO set and money supply along the
         // ACTIVE (best-trust) chain ONLY. The file-order pass above indexed
         // every block including orphaned side-chain blocks; replaying only
@@ -4335,6 +4555,15 @@ bool FastImportBlockFile()
             for (CBlockIndex* p = pindexBest; p; p = p->pprev)
                 vMain.push_back(p);
             std::reverse(vMain.begin(), vMain.end());
+
+            // File order includes side branches. Build pnext exclusively from
+            // the selected best-trust chain so kernel-modifier forward walks
+            // cannot follow whichever side-chain child appeared last.
+            for (const auto& item : mapBlockIndex)
+                item.second->pnext = nullptr;
+            for (size_t i = 1; i < vMain.size(); ++i)
+                vMain[i - 1]->pnext = vMain[i];
+
             printf("FastImportBlockFile: applying UTXO/supply along %d main-chain blocks...\n", (int)vMain.size());
             uiInterface.InitMessage(_("Building UTXO set (main chain)..."));
 
@@ -4342,6 +4571,13 @@ bool FastImportBlockFile()
             int nApplied = 0;
             for (CBlockIndex* pindex : vMain)
             {
+                if (fRequestShutdown)
+                {
+                    txdb.TxnAbort();
+                    return error("FastImportBlockFile: interrupted during active-chain replay at height %d",
+                                 pindex->nHeight);
+                }
+
                 // Genesis (height 0) is a hardcoded special block that is not
                 // re-read from disk this way; it contributes nothing to supply
                 // and the genesis-walk audit skips it identically. Carry the
@@ -4350,13 +4586,20 @@ bool FastImportBlockFile()
                 {
                     pindex->nMint = 0;
                     pindex->nMoneySupply = nRunningSupply; // still 0 here
-                    txdb.WriteBlockIndex(CDiskBlockIndex(pindex));
+                    if (!txdb.WriteBlockIndex(CDiskBlockIndex(pindex)))
+                    {
+                        txdb.TxnAbort();
+                        return error("FastImportBlockFile: failed to write genesis index");
+                    }
                     continue;
                 }
 
                 CBlock blockMain;
                 if (!blockMain.ReadFromDisk(pindex))
+                {
+                    txdb.TxnAbort();
                     return error("FastImportBlockFile: ReadFromDisk failed at height %d", pindex->nHeight);
+                }
 
                 int64_t nBlockValueIn = 0;
                 int64_t nBlockValueOut = 0;
@@ -4366,7 +4609,12 @@ bool FastImportBlockFile()
                 {
                     uint256 hashTx = tx.GetHash();
                     CDiskTxPos posThisTx(1, pindex->nBlockPos, nTxPos2);
-                    txdb.UpdateTxIndex(hashTx, CTxIndex(posThisTx, tx.vout.size()));
+                    if (!txdb.UpdateTxIndex(hashTx, CTxIndex(posThisTx, tx.vout.size())))
+                    {
+                        txdb.TxnAbort();
+                        return error("FastImportBlockFile: failed to write txindex %s",
+                                     hashTx.ToString().c_str());
+                    }
                     nTxPos2 += ::GetSerializeSize(tx, SER_DISK, CLIENT_VERSION);
 
                     nBlockValueOut += tx.GetValueOut();
@@ -4375,9 +4623,20 @@ bool FastImportBlockFile()
                         for (const CTxIn& txin : tx.vin)
                         {
                             CUtxoEntry uprev;
-                            if (txdb.ReadUtxo(txin.prevout.hash, txin.prevout.n, uprev))
-                                nBlockValueIn += uprev.nValue;
-                            txdb.EraseUtxo(txin.prevout.hash, txin.prevout.n);
+                            if (!txdb.ReadUtxo(txin.prevout.hash, txin.prevout.n, uprev))
+                            {
+                                txdb.TxnAbort();
+                                return error("FastImportBlockFile: missing spent UTXO %s:%u at height %d",
+                                             txin.prevout.hash.ToString().c_str(), txin.prevout.n,
+                                             pindex->nHeight);
+                            }
+                            nBlockValueIn += uprev.nValue;
+                            if (!txdb.EraseUtxo(txin.prevout.hash, txin.prevout.n))
+                            {
+                                txdb.TxnAbort();
+                                return error("FastImportBlockFile: failed to erase spent UTXO %s:%u",
+                                             txin.prevout.hash.ToString().c_str(), txin.prevout.n);
+                            }
                         }
                     }
                     for (unsigned int k = 0; k < tx.vout.size(); k++)
@@ -4391,16 +4650,40 @@ bool FastImportBlockFile()
                         utxo.fCoinBase = tx.IsCoinBase();
                         utxo.fCoinStake = tx.IsCoinStake();
                         utxo.nTxTime = tx.nTime;
-                        txdb.WriteUtxo(hashTx, k, utxo);
+                        if (!txdb.WriteUtxo(hashTx, k, utxo))
+                        {
+                            txdb.TxnAbort();
+                            return error("FastImportBlockFile: failed to write UTXO %s:%u",
+                                         hashTx.ToString().c_str(), k);
+                        }
                     }
                 }
 
                 pindex->nMint = nBlockValueOut - nBlockValueIn;
                 nRunningSupply += (nBlockValueOut - nBlockValueIn);
                 pindex->nMoneySupply = nRunningSupply;
-                txdb.WriteBlockIndex(CDiskBlockIndex(pindex));
+                if (!txdb.WriteBlockIndex(CDiskBlockIndex(pindex)))
+                {
+                    txdb.TxnAbort();
+                    return error("FastImportBlockFile: failed to update active block index at height %d",
+                                 pindex->nHeight);
+                }
 
-                if (++nApplied % 200000 == 0) { txdb.TxnCommit(); txdb.TxnBegin(); }
+                if (++nApplied % 200000 == 0)
+                {
+                    if (!txdb.TxnCommit())
+                    {
+                        txdb.TxnAbort();
+                        return error("FastImportBlockFile: active-chain batch TxnCommit failed at height %d",
+                                     pindex->nHeight);
+                    }
+                    if (!txdb.TxnBegin())
+                    {
+                        txdb.TxnAbort();
+                        return error("FastImportBlockFile: active-chain batch TxnBegin failed at height %d",
+                                     pindex->nHeight);
+                    }
+                }
                 if (nApplied % 5000 == 0)
                 {
                     int pct2 = (int)((int64_t)nApplied * 100 / (vMain.empty() ? 1 : vMain.size()));
@@ -4411,14 +4694,43 @@ bool FastImportBlockFile()
         }
 
         // Final commit
-        if (pindexBest)
+        if (fRequestShutdown)
         {
-            txdb.WriteHashBestChain(hashBestChain);
-
-            // Write sync checkpoint
-            Checkpoints::WriteSyncCheckpoint(hashBestChain);
+            txdb.TxnAbort();
+            return error("FastImportBlockFile: interrupted before final commit");
+        }
+        if (!txdb.WriteHashBestChain(hashBestChain))
+        {
+            txdb.TxnAbort();
+            return error("FastImportBlockFile: failed to persist best-chain hash");
+        }
+
+        // Write sync checkpoint
+        if (!Checkpoints::WriteSyncCheckpoint(hashBestChain))
+        {
+            txdb.TxnAbort();
+            return error("FastImportBlockFile: failed to persist sync checkpoint");
+        }
+
+        if (!txdb.TxnCommit())
+        {
+            txdb.TxnAbort();
+            return error("FastImportBlockFile: final database commit failed");
+        }
+        } // end try { ... FastImportBlockFile inner LOCK }
+        catch (const std::exception& e)
+        {
+            // Any exception escaping the import (allocation failure, database
+            // throw, unexpected validation throw) MUST NOT leak a partial
+            // commit. Abort the in-flight transaction before propagating.
+            txdb.TxnAbort();
+            return error("FastImportBlockFile: uncaught exception during import: %s", e.what());
+        }
+        catch (...)
+        {
+            txdb.TxnAbort();
+            return error("FastImportBlockFile: unknown exception during import");
         }
-        txdb.TxnCommit();
     }
 
     nTransactionsUpdated++;

src/main.h

@@ -141,6 +141,7 @@ CBlockIndex* FindBlockByHeight(int nHeight);
 bool ProcessMessages(CNode* pfrom);
 bool SendMessages(CNode* pto, bool fSendTrickle);
 bool LoadExternalBlockFile(FILE* fileIn);
+bool FastImportBlockFile();
 
 bool CheckProofOfWork(uint256 hash, unsigned int nBits);
 unsigned int GetNextTargetRequired(const CBlockIndex* pindexLast, bool fProofOfStake);

src/qt/introdialog.cpp

@@ -1,6 +1,9 @@
 #include "introdialog.h"
 #include "util.h"
 #include "bootstrap.h"
+#include "utxosnapshot.h"
+#include "checkpoints.h"
+#include "snapshotnet.h"
 
 #include <QSettings>
 #include <QVBoxLayout>
@@ -14,9 +17,27 @@
 #include <QCheckBox>
 #include <QApplication>
 
+#include <cstdio>
+#include <ctime>
+#include <set>
+
 #include <filesystem>
 
-#include <set>
+namespace fs = std::filesystem;
+
+// Convert QString to fs::path preserving non-ASCII characters on Windows.
+// On Windows, QString::toStdString() returns UTF-8 but std::filesystem::path
+// constructed from a narrow string then uses the ANSI code page, which
+// mangles UTF-8 paths. QString::toStdWString() + fs::path(std::wstring)
+// preserves them. On non-Windows platforms the UTF-8 path is correct.
+static fs::path qstringToPath(const QString& s)
+{
+#ifdef WIN32
+    return fs::path(std::wstring(s.toStdWString()));
+#else
+    return fs::path(s.toStdString());
+#endif
+}
 
 IntroDialog::IntroDialog(QWidget *parent) :
     QDialog(parent)
@@ -152,7 +173,7 @@ void IntroDialog::on_defaultRadio_toggled(bool checked)
 void IntroDialog::updateFreeSpace()
 {
     QString path = getDataDirectory();
-    std::filesystem::path fsPath(path.toStdString());
+    std::filesystem::path fsPath = qstringToPath(path);
 
     // Walk up to find an existing parent
     try {
@@ -211,14 +232,18 @@ bool IntroDialog::pickDataDirectory()
     }
 
     // If the saved path is the default, don't set -datadir (let normal defaults work)
-    QString defaultDir = QString::fromStdString(GetDefaultDataDir().string());
+    QString defaultDir = QString::fromStdString(
+        std::string(GetDefaultDataDir().u8string()));
     if (dataDir != defaultDir) {
-        mapArgs["-datadir"] = dataDir.toStdString();
+        // Pass the data dir to the daemon as UTF-8 bytes so a non-ASCII path
+        // on Windows isn't mangled by the ANSI code page (path::string() does
+        // that). The daemon side uses fs::u8path() to convert back.
+        mapArgs["-datadir"] = std::string(qstringToPath(dataDir).u8string());
     }
 
     // Ensure the directory exists
     try {
-        fs::create_directories(fs::path(dataDir.toStdString()));
+        fs::create_directories(qstringToPath(dataDir));
     } catch (const fs::filesystem_error &) {
         QMessageBox::critical(0, "Triangles",
             QString("Error: Could not create data directory \"%1\".").arg(dataDir));
@@ -227,17 +252,24 @@ bool IntroDialog::pickDataDirectory()
 
     // Auto-bootstrap: if no blockchain data exists, download automatically.
     // If data exists, offer optional re-download (unless user checked "don't ask again").
-    fs::path dataDirPath(dataDir.toStdString());
+    fs::path dataDirPath = qstringToPath(dataDir);
     bool needsBootstrap = Bootstrap::NeedsBootstrap(dataDirPath);
     bool userWantsBootstrap = false;
+    // Captured local-load error from the staged-snapshot probe below, surfaced
+    // in the HTTPS-failure dialog so users see why their snapshot was rejected.
+    std::string lastLocalLoadError;
 
     if (needsBootstrap)
     {
-        // No blockchain data — bootstrap automatically, just inform the user
+        // No blockchain data — bootstrap automatically, just inform the user.
+        // The actual mechanism (local snapshot vs HTTPS download vs network
+        // sync) is decided after probing the data directory; the dialog
+        // intentionally doesn't promise "downloading" because we may find a
+        // staged utxo-snapshot.bin and skip the network entirely.
         QMessageBox::information(0, "Triangles",
             "No blockchain data found.\n\n"
-            "Downloading the latest blockchain snapshot automatically.\n"
-            "This will only take a few minutes.");
+            "Setting up the wallet now — this only happens once.\n"
+            "If a local snapshot is available it will be loaded automatically.");
         userWantsBootstrap = true;
     }
     else if (!settings.value("bootstrapDontAsk", false).toBool())
@@ -263,59 +295,220 @@ bool IntroDialog::pickDataDirectory()
         userWantsBootstrap = (ret == QMessageBox::Yes);
     }
 
-        if (userWantsBootstrap)
-        {
-            std::string host = Bootstrap::DEFAULT_HOST;
-            std::string strError;
+    if (userWantsBootstrap)
+    {
+        std::string host = Bootstrap::DEFAULT_HOST;
+        std::string strError;
 
-            QProgressDialog progress("Downloading blockchain snapshot...", "Cancel",
-                                     0, 100, 0);
-            progress.setWindowTitle("Triangles - Bootstrap");
-            progress.setWindowModality(Qt::ApplicationModal);
-            progress.setMinimumDuration(0);
-            progress.setValue(0);
+        // First-run local-snapshot probe: if utxo-snapshot.bin is already in the
+        // data directory (placed there by the user, an installer, or a
+        // previous P2P fetch), load it directly. This avoids the HTTPS
+        // bootstrap path entirely on first run.
+        fs::path stagedSnap = dataDirPath / "utxo-snapshot.bin";
+        std::error_code stagedEc;
+        // Use the non-throwing error_code overload and probe symlink
+        // status separately. We reject symlinks: an auto-loaded snapshot
+        // is supposed to be a file the user placed in the data dir, not a
+        // symlink an attacker could redirect to anything; if the user
+        // genuinely wants to symlink, they can resolve it and copy the
+        // file. A symlink_status probe error (broken perms, ENOENT on a
+        // parent component) is treated as "not present" and falls through
+        // to HTTPS bootstrap.
+        fs::file_status symSt = fs::symlink_status(stagedSnap, stagedEc);
+        bool stagedPresent = (!stagedEc &&
+                              fs::is_symlink(symSt) == false &&
+                              fs::is_regular_file(symSt));
+        if (stagedEc) {
+            printf("IntroDialog: cannot probe staged snapshot path (%s); skipping local load\n",
+                   stagedEc.message().c_str());
+            stagedPresent = false;
+        }
+        if (stagedPresent) {
+            printf("IntroDialog: found staged utxo-snapshot.bin in data dir, attempting local load...\n");
 
-            auto progressFn = [&progress](int64_t bytesDownloaded, int64_t totalBytes) {
-                if (totalBytes > 0) {
-                    int pct = (int)((bytesDownloaded * 100) / totalBytes);
-                    progress.setValue(pct);
-                    progress.setLabelText(
-                        QString("Downloading blockchain snapshot... %1 MB / %2 MB")
-                        .arg(bytesDownloaded / (1024*1024))
-                        .arg(totalBytes / (1024*1024)));
+            // Validate the staged file against the compiled-in hash before
+            // touching the chain DB. This prevents loading a stale or wrong
+            // snapshot from a previous install into a fresh data dir.
+            int snapHeight = Checkpoints::GetBestSnapshotHeight();
+            uint256 expectedHash;
+            bool hashOk = (snapHeight > 0) &&
+                           Checkpoints::GetSnapshotHash(snapHeight, expectedHash);
+
+            std::string localErr;
+            bool loaded = false;
+            if (hashOk) {
+                uint256 actualHash;
+                std::string hashErr;
+                if (SnapshotNet::ComputeSnapshotFileHash(stagedSnap, actualHash, hashErr)) {
+                    if (actualHash != expectedHash) {
+                        // Staged file is for a different release or otherwise
+                        // doesn't match this build's compiled-in hash. Do NOT
+                        // delete it — the user may have staged it intentionally,
+                        // or it may belong to another release. Quarantine with
+                        // a unique suffix so a previously quarantined file is
+                        // never overwritten. If no free name can be found (or
+                        // the rename itself fails for perms/locks), leave the
+                        // original in place and report the exact error so the
+                        // user can recover manually.
+                        std::error_code rmEc;
+                        fs::path quarantine;
+                        bool foundFreeName = false;
+                        // Capture the timestamp once — repeated time() calls
+                        // inside the loop would just shift the suffix but add
+                        // nothing useful, and could overflow on busy systems.
+                        const std::string quarantinePrefix =
+                            stagedSnap.string() + ".rejected." +
+                            std::to_string(::time(nullptr)) + ".";
+                        // Collision-safe suffix: timestamp + a small loop
+                        // counter. Two rejections within the same second
+                        // (e.g. double-clicked bootstrap dialog) still get
+                        // distinct destinations. The loop caps at 1000 attempts;
+                        // if every candidate is occupied we refuse to rename
+                        // (overwriting an earlier quarantined file would lose
+                        // the user's data and is worse than just reporting the
+                        // conflict).
+                        for (int attempt = 0; attempt < 1000; ++attempt) {
+                            std::string name = quarantinePrefix +
+                                               std::to_string(attempt);
+                            quarantine = name;
+                            std::error_code probeEc;
+                            if (!fs::exists(quarantine, probeEc) && !probeEc) {
+                                foundFreeName = true;
+                                break;
+                            }
+                        }
+                        if (!foundFreeName) {
+                            // All 1000 candidate names were already taken.
+                            // This is extremely unlikely in normal operation
+                            // but if it happens, surface an honest error —
+                            // a "no space on device" message would be
+                            // misleading here.
+                            rmEc = std::make_error_code(std::errc::file_exists);
+                        } else {
+                            fs::rename(stagedSnap, quarantine, rmEc);
+                        }
+                        if (rmEc) {
+                            localErr = "staged utxo-snapshot.bin hash does not match this release "
+                                       "(expected " + expectedHash.ToString().substr(0, 16) +
+                                       ", got " + actualHash.ToString().substr(0, 16) +
+                                       "), AND quarantine failed (" + rmEc.message() +
+                                       "). Leave the original in place and review it manually: " +
+                                       stagedSnap.string();
+                        } else {
+                            localErr = "staged utxo-snapshot.bin hash does not match this release "
+                                       "(expected " + expectedHash.ToString().substr(0, 16) +
+                                       ", got " + actualHash.ToString().substr(0, 16) +
+                                       "). File moved to " + quarantine.filename().string() +
+                                       " — review or delete it manually.";
+                        }
+                        printf("IntroDialog: %s\n", localErr.c_str());
+                    } else {
+                        loaded = UtxoSnapshot::LoadSnapshot(stagedSnap, dataDirPath,
+                                                             localErr, /*requireCheckpoint=*/true);
+                    }
                 } else {
-                    progress.setLabelText(
-                        QString("Downloading blockchain snapshot... %1 MB")
-                        .arg(bytesDownloaded / (1024*1024)));
-                }
-                QApplication::processEvents();
-            };
-
-            // Try the fast UTXO snapshot path first (matches daemon behavior in init.cpp).
-            // The legacy DownloadBootstrap() is hard-disabled in bootstrap.cpp — it always
-            // returns false with "Legacy file-list bootstrap is disabled". Calling it here
-            // would make the GUI wallet unable to bootstrap a fresh install.
-            std::string utxoError;
-            bool success = Bootstrap::DownloadUtxoSnapshot(host, dataDirPath, progressFn, utxoError);
-            if (!success) {
-                // Fall back to legacy bootstrap path (will fail with "disabled" error, but
-                // surfaces the real error if the snapshot path had a different failure).
-                std::string legacyError;
-                if (Bootstrap::DownloadBootstrap(host, dataDirPath, progressFn, legacyError)) {
-                    success = true;
-                } else {
-                    strError = "UTXO snapshot: " + utxoError + " | Legacy: " + legacyError;
+                    localErr = "cannot hash staged snapshot: " + hashErr;
                 }
+            } else {
+                localErr = "no compiled-in snapshot hash available in this release";
             }
-            if (!success) {
+
+            if (loaded) {
+                printf("IntroDialog: loaded staged utxo-snapshot.bin successfully\n");
+                return true;
+            }
+
+            // Staged file failed to load — fall through to HTTPS bootstrap.
+            // Remember the local-load reason so we can show it to the user
+            // if HTTPS also fails (the failure dialog below concatenates it).
+            printf("IntroDialog: staged snapshot unusable (%s); falling back to network bootstrap\n",
+                   localErr.c_str());
+            lastLocalLoadError = localErr;
+        }
+
+        QProgressDialog progress("Downloading blockchain snapshot...", "Cancel",
+                                 0, 100, 0);
+        progress.setWindowTitle("Triangles - Bootstrap");
+        progress.setWindowModality(Qt::ApplicationModal);
+        progress.setMinimumDuration(0);
+        progress.setValue(0);
+
+        auto progressFn = [&progress](int64_t bytesDownloaded, int64_t totalBytes) {
+            if (totalBytes > 0) {
+                int pct = (int)((bytesDownloaded * 100) / totalBytes);
+                progress.setValue(pct);
+                progress.setLabelText(
+                    QString("Downloading blockchain snapshot... %1 MB / %2 MB")
+                    .arg(bytesDownloaded / (1024*1024))
+                    .arg(totalBytes / (1024*1024)));
+            } else {
+                progress.setLabelText(
+                    QString("Downloading blockchain snapshot... %1 MB")
+                    .arg(bytesDownloaded / (1024*1024)));
+            }
+            QApplication::processEvents();
+        };
+
+        // Try the fast UTXO snapshot path. The GUI has already probed the data
+        // dir for a staged utxo-snapshot.bin above; if that didn't find one,
+        // DownloadUtxoSnapshot is the canonical HTTPS path to the bootstrap
+        // server. TLS validation is now handled in bootstrap.cpp's StartTLS
+        // via a layered trust store (exedir cacert.pem → SSL_CERT_FILE →
+        // system default paths → embedded ISRG X1 + X2 as belt-and-suspenders),
+        // so this should succeed on Windows GUI builds where the Qt-bundled
+        // libssl-3-x64.dll ships without a default cert path. The system-path
+        // call is trusted on its return value (OpenSSL's hashed-directory
+        // lookups are lazy and would otherwise show 0 eagerly loaded store
+        // objects even on a valid install); the embedded fallbacks are
+        // always attempted as cross-sign resilience and become load-bearing
+        // on a stripped Windows GUI with no cacert.pem and no usable system
+        // CA directory.
+        std::string utxoError;
+        bool success = Bootstrap::DownloadUtxoSnapshot(host, dataDirPath, progressFn, utxoError);
+        if (!success) {
+            strError = utxoError;
+        }
+        if (!success) {
+            // The TLS-detection strings are matched against the standard error
+            // messages produced by the bootstrap OpenSSL path; they cover
+            // the common GUI-bundled OpenSSL failure modes without dumping
+            // the raw error to the user.
+            bool isTlsError = (strError.find("TLS handshake failed") != std::string::npos ||
+                               strError.find("certificate verify failed") != std::string::npos ||
+                               strError.find("TLS certificate verification failed") != std::string::npos);
+            if (isTlsError) {
+                QString localNote;
+                if (!lastLocalLoadError.empty()) {
+                    localNote = QString("\n\nLocal snapshot note: %1")
+                        .arg(QString::fromStdString(lastLocalLoadError));
+                }
+                QMessageBox::warning(0, "Triangles",
+                    QString("Could not download blockchain snapshot automatically.\n\n"
+                            "The bundled network stack cannot validate the certificate of the\n"
+                            "bootstrap server. To skip this, place a file named\n"
+                            "    utxo-snapshot.bin\n"
+                            "in your Triangles data directory:\n"
+                            "    %1\n\n"
+                            "Then restart the wallet — the snapshot will load automatically.\n\n"
+                            "Otherwise, the wallet will sync from the network instead.%2")
+                        .arg(dataDir)
+                        .arg(localNote));
+            } else {
+                QString localNote;
+                if (!lastLocalLoadError.empty()) {
+                    localNote = QString("\n\nLocal snapshot note: %1")
+                        .arg(QString::fromStdString(lastLocalLoadError));
+                }
                 QMessageBox::warning(0, "Triangles",
                     QString("Could not download blockchain snapshot:\n%1\n\n"
-                            "The wallet will sync from the network instead.")
-                    .arg(QString::fromStdString(strError)));
-            } else {
-                progress.setValue(100);
+                            "The wallet will sync from the network instead.%2")
+                        .arg(QString::fromStdString(strError))
+                        .arg(localNote));
             }
+        } else {
+            progress.setValue(100);
         }
+    }
 
     return true;
 }
@@ -339,8 +532,8 @@ bool IntroDialog::migrateDataDirectory(const QString& oldPath, const QString& ne
 {
     namespace fs = std::filesystem;
 
-    fs::path srcDir(oldPath.toStdString());
-    fs::path dstDir(newPath.toStdString());
+    fs::path srcDir = qstringToPath(oldPath);
+    fs::path dstDir = qstringToPath(newPath);
 
     if (!fs::exists(srcDir) || !fs::is_directory(srcDir))
         return false;

src/test/Checkpoints_tests.cpp

@@ -11,8 +11,11 @@ BOOST_AUTO_TEST_CASE(hardened_checkpoints_match_current_chain)
     BOOST_CHECK(Checkpoints::CheckHardened(9000, uint256("0x00000000019ef6b2f5e7c324c7d083ee94502305aabc7e9cd73a7fb2a57bb8db")));
     BOOST_CHECK(Checkpoints::CheckHardened(9001, uint256("0x6d5c6c5f201cc9e59659ee0da30d1430dc6bf3b12a8ff4c3864ab8d6286b0007")));
     // Finality pins added 2026-07-01 (the old 2186940 pin was superseded).
-    BOOST_CHECK(Checkpoints::CheckHardened(2205000, uint256("0x6bdd3c5e5a32e1dd9a70e705f1a28d1dd84929f89579bd2696d41bc87f39446f")));
-    BOOST_CHECK(Checkpoints::CheckHardened(2206004, uint256("0xb34e8e6a7bb7f52167d81aaad4d26f87a876898fdd0fce860916fc1aaf9a2a46")));
+    // After the operator rollback to 2,172,037 (cycle-32, 2026-08-06), the
+    // 2205000/2206004 pins are no longer in the map (those block heights are
+    // above the new canonical tip and reference non-existent blocks). The new
+    // highest entry is 2172037.
+    BOOST_CHECK(Checkpoints::CheckHardened(2172037, uint256("0x52b12f0970191505d9982449875822b78f075d7d76307abed45e7132f5fa2f16")));
 }
 
 BOOST_AUTO_TEST_CASE(hardened_checkpoints_reject_wrong_hashes_and_allow_unknown_heights)
@@ -21,19 +24,23 @@ BOOST_AUTO_TEST_CASE(hardened_checkpoints_reject_wrong_hashes_and_allow_unknown_
 
     BOOST_CHECK(!Checkpoints::CheckHardened(9000, wrongHash));
     BOOST_CHECK(!Checkpoints::CheckHardened(9001, wrongHash));
-    BOOST_CHECK(!Checkpoints::CheckHardened(2205000, wrongHash));
-    BOOST_CHECK(!Checkpoints::CheckHardened(2206004, wrongHash));
+    BOOST_CHECK(!Checkpoints::CheckHardened(2172037, wrongHash));
 
     // 2186940/2186941 are no longer pinned (superseded by the 2205000+
-    // pins), so any hash is allowed at those heights.
+    // pins), and after the cycle-32 operator rollback the 2205000+ pins
+    // themselves are gone. Any hash is allowed at those heights.
     BOOST_CHECK(Checkpoints::CheckHardened(2186940, wrongHash));
     BOOST_CHECK(Checkpoints::CheckHardened(2186941, wrongHash));
+    BOOST_CHECK(Checkpoints::CheckHardened(2205000, wrongHash));
+    BOOST_CHECK(Checkpoints::CheckHardened(2206004, wrongHash));
     BOOST_CHECK(Checkpoints::CheckHardened(42, wrongHash));
 }
 
 BOOST_AUTO_TEST_CASE(total_blocks_estimate_tracks_latest_hardened_checkpoint)
 {
-    BOOST_CHECK(Checkpoints::GetTotalBlocksEstimate() >= 2205000);
+    // After operator rollback to 2,172,037, GetTotalBlocksEstimate() returns
+    // 2,172,037 (the new highest compiled checkpoint).
+    BOOST_CHECK_EQUAL(Checkpoints::GetTotalBlocksEstimate(), 2172037);
 }
 
 BOOST_AUTO_TEST_SUITE_END()

src/test/consensus_safety_tests.cpp

@@ -680,11 +680,11 @@ BOOST_AUTO_TEST_CASE(reorg_guard_fails_closed_when_checkpoint_pointer_null)
     BOOST_CHECK(src.find("nHardenedCheckpointHeight = Checkpoints::GetLastCheckpointHeight()")
                 != std::string::npos);
 
-    // (c) The guard fires for any fork point at or below the resolved
+    // (c) The guard fires for any fork point strictly below the resolved
     //     checkpoint height — independent of whether the resolution came
     //     from the pointer or the compiled map. The literal pattern that
-    //     matters is `pfork->nHeight <= nHardenedCheckpointHeight`.
-    BOOST_CHECK(src.find("pfork->nHeight <= nHardenedCheckpointHeight")
+    //     matters is `pfork->nHeight < nHardenedCheckpointHeight`.
+    BOOST_CHECK(src.find("pfork->nHeight < nHardenedCheckpointHeight")
                 != std::string::npos);
 
     // (d) The old guard pattern that short-circuited on the null pointer
@@ -699,40 +699,49 @@ BOOST_AUTO_TEST_CASE(reorg_guard_fails_closed_when_checkpoint_pointer_null)
 // ─── Off-by-one hardening: guard operator + bootstrap boundary semantics ──
 // Adversarial review (Codex round 3 on 6116cff) flagged that the source-grep
 // test reorg_guard_fails_closed_when_checkpoint_pointer_null could let through
-// a future refactor that weakens the boundary (e.g., changing `<=` to `<`)
+// a future refactor that weakens the boundary (e.g., changing `<` to `<=`)
 // or splits the guard across files. This test pins:
-//   (i) the operator used by the guard (must be `<=`),
+//   (i) the operator used by the guard (must be `<`),
 //  (ii) the runtime return value of Checkpoints::GetLastCheckpointHeight()
 //       against the actual compiled map (must equal the highest compiled
 //       checkpoint height),
-// (iii) that the literal RejectReason message uses the "at or below" wording
-//       (matches `<=`).
+// (iii) that the literal RejectReason message uses the "below" wording
+//       (matches `<`).
+//
+// Cycle-33 update: the operator is now strict `<` (not `<=`). Reason: a fork
+// whose common ancestor EQUALS the checkpoint height preserves the checkpoint
+// block (which both chains share) and only replaces blocks AFTER the
+// checkpoint. If the new chain has higher trust, it should win per the
+// standard trust-vs-snapshot fork-selection rule. Rejecting such a reorg
+// would cause honest nodes that observed different height-(checkpoint+1) blocks
+// to remain split forever even when they agree on the checkpoint.
 BOOST_AUTO_TEST_CASE(reorg_guard_offbyone_hardening)
 {
-    // (i) The guard predicate uses `<=`, NOT `<` or `>=`.
-    //     A regression that introduced `pfork->nHeight < nHardenedCheckpointHeight`
-    //     would let a fork exactly at the checkpoint height through.
+    // (i) The guard predicate uses `<`, NOT `<=` or `>=`.
+    //     A regression that introduced `pfork->nHeight <= nHardenedCheckpointHeight`
+    //     would cause a permanent chain split when honest nodes see different
+    //     height-(checkpoint+1) blocks.
     std::string src = readEntireFile("src/main.cpp");
     BOOST_REQUIRE(!src.empty());
-    BOOST_CHECK(src.find("pfork->nHeight <= nHardenedCheckpointHeight")
-                != std::string::npos);
     BOOST_CHECK(src.find("pfork->nHeight < nHardenedCheckpointHeight")
+                != std::string::npos);
+    BOOST_CHECK(src.find("pfork->nHeight <= nHardenedCheckpointHeight")
                 == std::string::npos);
     BOOST_CHECK(src.find("pfork->nHeight >= nHardenedCheckpointHeight")
                 == std::string::npos);
 
-    // (iii) The reject message wording matches `<=` ("at or below").
-    BOOST_CHECK(src.find("\"REORGANIZE: REJECTED — fork point %d is at or below")
+    // (iii) The reject message wording matches `<` ("below").
+    BOOST_CHECK(src.find("\"REORGANIZE: REJECTED — fork point %d is below")
                 != std::string::npos);
 
     // (ii) Runtime: GetLastCheckpointHeight() returns the highest compiled
     //      checkpoint height on mainnet. Verified against the actual binary.
     int nCompiled = Checkpoints::GetLastCheckpointHeight();
     BOOST_CHECK(nCompiled > 0);  // sanity: compiled map populated
-    // Must equal the highest key in the compiled map (2224763 as of v6.2.6.0;
+    // Must equal the highest key in the compiled map (2172037 as of cycle-33;
     // this assertion locks the value at the time the binary was built, so
     // a regression that drops a checkpoint would also fail here).
-    BOOST_CHECK_EQUAL(nCompiled, 2224763);
+    BOOST_CHECK_EQUAL(nCompiled, 2172037);
 }
 
 // ─── Duplicate-guard detection: variable referenced only in allowed files ─
@@ -873,4 +882,46 @@ BOOST_AUTO_TEST_CASE(hardened_checkpoint_no_rogue_guard_in_other_files)
         "trusting its PASS.");
 }
 
+BOOST_AUTO_TEST_CASE(reindex_reconstruction_is_explicit_and_fail_closed)
+{
+    // Pin the startup bridge and the fail-closed invariants structurally. The
+    // end-to-end test separately reconstructs the production blk0001.dat;
+    // these checks prevent a refactor from silently returning to the old
+    // "wipe DB, create genesis, never import" behavior.
+    const std::filesystem::path here(__FILE__);
+    const std::filesystem::path root = here.parent_path().parent_path().parent_path();
+
+    std::ifstream initFile(root / "src" / "init.cpp");
+    std::ifstream mainFile(root / "src" / "main.cpp");
+    BOOST_REQUIRE(initFile.good());
+    BOOST_REQUIRE(mainFile.good());
+
+    const std::string initSrc((std::istreambuf_iterator<char>(initFile)),
+                              std::istreambuf_iterator<char>());
+    const std::string mainSrc((std::istreambuf_iterator<char>(mainFile)),
+                              std::istreambuf_iterator<char>());
+
+    BOOST_CHECK(initSrc.find("const bool fReindex = GetBoolArg(\"-reindex\", false)") != std::string::npos);
+    BOOST_CHECK(initSrc.find("if (!FastImportBlockFile())") != std::string::npos);
+    BOOST_CHECK(initSrc.find("else if (!LoadBlockIndex())") != std::string::npos);
+    BOOST_CHECK(mainSrc.find("if (fRequestShutdown)") != std::string::npos);
+    BOOST_CHECK(mainSrc.find("reindex is incomplete") != std::string::npos);
+    BOOST_CHECK(mainSrc.find("interrupted during active-chain replay") != std::string::npos);
+    BOOST_CHECK(mainSrc.find("unexpected or duplicate genesis block") != std::string::npos);
+    BOOST_CHECK(mainSrc.find("invalid record magic") != std::string::npos);
+    BOOST_CHECK(mainSrc.find("malformed block payload") != std::string::npos);
+    BOOST_CHECK(mainSrc.find("trailing bytes at file offset") != std::string::npos);
+    BOOST_CHECK(mainSrc.find("block file was not consumed exactly") != std::string::npos);
+    BOOST_CHECK(mainSrc.find("block failed context-free validation") != std::string::npos);
+    BOOST_CHECK(mainSrc.find("hardened checkpoint mismatch") != std::string::npos);
+    BOOST_CHECK(mainSrc.find("selected chain does not reach the newest compiled checkpoint") != std::string::npos);
+    BOOST_CHECK(mainSrc.find("nFileSize > (int64_t)std::numeric_limits") != std::string::npos);
+    BOOST_CHECK(mainSrc.find("std::unique_ptr<FILE") != std::string::npos);
+    BOOST_CHECK(mainSrc.find("item.second->pnext = nullptr") != std::string::npos);
+    BOOST_CHECK(mainSrc.find("failed to persist best-chain hash") != std::string::npos);
+    BOOST_CHECK(mainSrc.find("final database commit failed") != std::string::npos);
+    BOOST_CHECK(initSrc.find("REINDEX_INCOMPLETE") != std::string::npos);
+    BOOST_CHECK(initSrc.find("SyncReindexMarker") != std::string::npos);
+}
+
 BOOST_AUTO_TEST_SUITE_END()